R2 whistles
 

NFHS rules

I am R2, working with an R1 that I have worked with many times before. HS Varsity match.

Rally in progress, ball is sent over the net by team S, kind of a looping path, team R player takes a swipe at it to hit it but just barely ticks the ball, I hear, as well as see the contact. Team R then passes, sets, and attacks the ball. I see this periphially as I am now on the team S side.

I am discreetly signally a four contact violation to my partner, but she does not see me. Team S coach is yelling "FOUR, FOUR". I blow my whistle as I am 100% sure of the violation.

Question.....is it proper for the R2 to whistle on that call?

This is something you should cover in your prematch.

I would discreetly, then less and less discreetly, keep trying to get your partner's attention during the rally. I would be inclined to let the rally play out, then ask the R1 to invite me over to share information.

Though you are certain a fault occurred, this is something that is ultimately the R1's final decision, and not something you want to run the risk of getting into trouble calling yourself as R2.

You did the right thing in trying to get the call right, but you want to make sure your partner has every opportunity to look at you and make that call first.