Need a little more info. WHEN do these fouls occur? If they occur before the ball is actually kicked, then the Basic Spot is the previous spot. However, if they occur “…during a scrimmage kick…” (10-2-3-b), then they are considered as occurring after team B is in team possession, and PSK applies.
This can seem a bit tricky, because there is difference between “a scrimmage kick” and a “scrimmage kick play.” A “scrimmage kick” is literally that - from the moment the kicker actually kicks the ball, until it comes into player possession or becomes dead. A “scrimmage kick play” is the portion of a down that actually begins at the snap, and ends when the kick ends (by player possession or the ball becoming dead). For this question regarding Team B fouls during a scrimmage kick down, we need to know if they occurred before the ball was kicked, during the scrimmage kick, or after the end of the kick (and the ball remained alive when the foul occurred). B78’s foul could easily have occurred prior the kick, and would be a previous spot enforcement. B12’s foul most likely occurred during the kick (and, by philosophy, a foul against a flyer/gunner who is generally up to speed and trying to get past a defender is to be considered as happening during the kick, even if, technically, the ball hadn’t actually been kicked at the moment the foul occurred), and would be PSK. Fouls that occur after the end of the kick comply with Basic Spot/3 & 1 enforcement. The calling official MUST know the status of the ball when the foul occurred, and report that to the R.