muff or bobble

[c it first]

NFHS - R1 signals for fair catch . Scrimmage kick is very high and K1 does a good job getting down the field to cover. R does not make a clean catch and is immediately hit by K1. The ball is recovered by K2. It can't be a fumble because it was not possesed by R1. It's hard to say R1 muffed it because the contact by K1 was immediate. I read (6-5-6). Can K1 cause the muff? Does K need to allow R any amount of time to gain possession?