PSK or not?
 

4th down and 9 from A's 30. B has 11 players on field, B1 runs on to field and B2 starts running off, but does not make it off prior to the snap. Flag for illegal participation simultaneous with snap and prior to kick. Need some help with this one.

It couldn't be a post-scrimmage kick enforcement because the foul occurred simultaneously w the snap. The ball of course hadn't gone beyond the expanded neutral zone, let alone having been kicked there.

Think about the rationale for PSK enforcement too. The covering official thought the 12th player had enough presence on the field for it to be illegal participation, not just a substitution foul or a nothing. Maybe team A had a kick-pass option on, and that 12th player looked like he could've covered a receiver. PSK was adopted to treat situations in which there was already a team R w presumptive possession of the ball, not situations in which team A might never have kicked.

I hate to be crass but did you check the book before posting?

1. This is illegal substitution, not participation, unless he participated but it doesn't sound like he did. 3-7-4

2. PSK fouls explicitly exclude illegal substitution and participation fouls. 2-16-2-h

So you have a 5 yard penalty against Team R enforced from the previous spot. Team K can accept and replay the down, 4th and 4 at the K-35 or they can decline it and accept the result of the play.

You're right, it's substitution not participation. Thanks.