WE are lucky in that it is pretty well understood by the teams in the juniors over here. Blow the foul, quick word with the player and signal his coach. Coach subs him off and you say 'give him 5' or '10' or whatever ou think it deserves. Generally, you don't need to keep track, as the coaches are pretty OK with the way it is and tend to follow it pretty well. With RoRo subs it's easy to do, the eight year old learns that if he acts in an inappropriate way he will have to leave the field.
In theory, after I've spoken to him, the coach and/or a parent will give the rollicking, and he gets the chance to come back on and make amends.