I have to respectfully disagree with the above interpretation of 10-4-5d. I do agree with Ralph in that the foul in the OP did not affect the final result of the play. However, by rule the foul did happen during a Loose Ball Play per (2-33-1a & 10-3-1a) and I see no exceptions to allow a foul by R during a Free Kick that results in a TB to be enforced at the succeeding spot. My point being, 10-4-5d was in the books long before there was talk about "eliminating re-kicks."
I have not been able to find the actual year that 10-4-5d was created, I was able to find the following on FootballRefs.org concerning the 1996 Rule Changes:
"The basic spot of enforcement is now the 20 yard line instead of the goal line for plays which result in a touchback"