Contact is not a requirement.
I would like to see some attempt at catch; but no, I guess is not technically needed (i.e. could be blocked before had the opportunity to attempt a catch).
As described, this play is a matter of judgement and I believe either could be supported.
Had R stood his ground, the judgement likely would have gone in his favor (his retreat didn't help his case; could've been construed as deciding to play the bounce). Had he signaled FC and stood his ground then even a better chance to get the KCI.
If you threw a flag on this play and the WH waived off, I would not let that deter you from throwing a flag next time something similar occurs. Some WHs are likely on the same page as you.