Courtesy Runner -Fed Rules -Kinda
 

Doing a local HS tournament. Like Wade nice weather. Tourney rules were go to tiebreaker in top of 8th. Our section uses ASA tiebreaker rules. So top of 8th the player to be put at 2nd base is the pitcher. Team brings in their courtesy runner for F1. Opposing head coach gets in a huffy, saying that not allowed in tiebreakers. I rule it's a legal move and away we go. I get to car and read my ASA rulebook and I find nothing that says can't use a courtesy runner in that sitch .

Did I miss something ?

No. It is legal to use a CR for F1 / F2 if they are the runner under the tie breaker rule.