Do you still have interference?

[SC Ump]

I assume you are not talking about malicious contact, which would mean that you are saying R1 clearly "illegally impedes, hinders or confuses the fielder". But if BR was at 1B already, how was F6 impeded, hindered or confused?

If there were any doubt in my mind as to whether there was a play being made on BR, e.g. turn the wrong way, did F6 make an errant throw because of R1's actions, etc., I would rule it interference, but otherwise, I'd probably just warn the player.