fortran, 220 bytes

Result

AC

Duration

751ms

Code [DL]

program x
character(len=50)::s
read(*,'(a)')s
print('(a)'),s
j=index(s,'T')
k=0
do while(k.eq.0)
read(*, '(a)')s
s(j:j)='R'
k=index(s,'K')
if(k.gt.0)then
forall(i=k:j)s(i:i)='R'
end if
print('(a)'),s
end do
end program x

stdin

                                      T           
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                                                  
                      K                           

stdout

                                      T           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                                      R           
                      RRRRRRRRRRRRRRRRR           

stderr

strace