What is the call?

[CecilOne]

A factor that is not clear is whether F5 "trying to recover the ball" means he moved or just stayed in place getting it off the ground. If he moved, then it probably was obstruction. If he didn't move, meaning he was where the runner should have avoided him in the first place, it might be interference. I guess that's similar to what Roger siad, without the measurement. As usual, YHTBT, but my first instinct was obstruction, especially after some other recent discussons on this forum.
The PU comment is meaningless because if he didn't see the boot, he couldn't know what F5 was doing after it. Also, analyzing the "50/50 split in our association" is dependent on why, so no comment.

I don't agree that when "you have a collision, you've got something". There are non-call collisions, especially when the ball and both players arrive at the same time.