fish-shell-pure, 186 bytes

Result

AC

Duration

1310ms

Code [DL]

read s
set t (string split \  (string match -nr T $s))[1]
while read p
echo $s
set k (string match -r " *K" $p)
[ $k ]&&echo $k(string repeat -n (math $t-(string length $k)) @)&&exit
end

stdin

           T                                      
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
  K                                               

stdout

           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
           T                                      
  K@@@@@@@@@

stderr

strace