May seem odd, but this is a previous spot enforcement. This is still a free kick play, since the ball has not changed team possession, or become dead prior to the foul occurring. Technically, for free kick plays, the previous spot is the Basic Spot, and, by 3&1, fouls by B are enforced at the Basic Spot.
A, kickoff, A-45, PC=25, GC=legal touch of kicked ball in field of play (penalty accepted), OR, B, 1/10, B-25, PC=25, GC=snap (penalty declined).
Doubt Team A will let B have the ball at the B-25. Wouldn't even offer the option. Obvious they will accept the penalty.
Robert