Good question. My opinion is team B unknowingly gained a possible advantage by fouling, even though they have no clue that by fouling the clock may start on the RFP. With that, I will probably look at the chains and determine we are short of the first down. Clock will start on the snap.

Canadian Ruling
 

(I will assume it was third down since we have no fourth down.)

In Canada we have no incidental face mask. Players need to avoid grasping the mask or they get dinged for a 15 yard penalty, period.

Our UR penalties get enforced from PLS or PBD at A's option. So it would be half the distance from the 17, Team A 1st and goal at the 8.5 yard line. On any accepted penalty in the last three minutes, the clock will start on the snap with 0:03 left.

I think you are wrong here. NFHS you would not extend the game, a penalty by the offense does not extend the period.

REPLY: I think you better check on that. See NF 3-3-3.

That's why I posted that situation. Many fans, coaches, and players think that the period is only extended for a defensive penalty. Any accepted penalty (offense or defense), except for a LOD penalty, extends the period for one untimed down. But in the situation I posted, it was not a LOD, so therefore an untimed down.

I remember discussing years ago with a coach the following situation:

A's ball, 1st and 10 from midfield. Team A trails by 2 points with 0:05 left in the 4th quarter. A1 throws a short pass to A2, which advances to B's 15. As B players converge on A2, A3 slips behind the defenders and A2 completes a forward pass to A3. A3 enters the EZ untouched. Ruling?

(Before the LOD rule change, my gut tells me that it's 2nd and 15 from A's 45. But at the time of the discussion, we thought it would be 1st and 10 from B's 20. One untimed down. A lines up and kicks a FG to win the game. Of course now, the penalty is accepted, and game over.)

Forgot there needs to be a loss of down.