illegal substitution
 

team B(defense) has 12 men on the field, B12 tries to run off the field but does not make it before the ball is snapped. we were not able to flag before snap because it was a hurry up and we did not get them counted in time. would this be a illegal substitution because the player did not participate? what are the options and enforcement?

It is a foul simultaneous with the snap. For all fouls sim w/ the snap, the BSpot is the PS, so A can decline and take the result of the play, or enforce the 5 yard penalty from the PS and replay the down.

if the player participates and we have an illegal participation, than do we add that to the end of run? i was just wondering the difference because aren't they both at the snap.

Enforce both from PS.