The penalty for interference is a spot foul, automatic first down.
Seriously - this is a VERY HTBT situation. If runner did (in the umpire's judgement) interfere with F6's ability to make the catch, you have interference (immediate dead ball and an out on the runner, BR to 1st).
If she didn't (again - in the umpire's judgement) intefere, and F6 just had a brainfart, there is nothing to call. Either way, it's judgement and very hard (for us) to call without seeing it.
It's hard (not impossible!) to call interference on a runner in this sitch without either A) contact, or B) intent, but the fielder DOES have the right of way here. Problem is that there is a HUGE grey area of cause and effect on a play like this, and for it to be interference, the runners actions have to have an effect on the fielder.