Since the hold by R occurs beyond the ENZ while the kick in still in progress, we have PSK enforcement. The basic spot is where the kick ends, so enforce 10 yards from R-48 yard line. R will put ball into play at their 38.
Just for completeness, if for some reason K declines the penalty, R can take the ball at the spot of first touching (K-45 yard line). However, this spot of first touching is canceled for any accepted foul during the down. 6-2-5 (I had to check out this last part as I didn't realize any accepted penalty did this, I thought it was only if R fouled after the first touching)