[FMadera]

Not sure on NFHS guidance, but here is what I was instructed by a national level official.

If you as R1/referee see the net violation, blow your whistle. Give your partner time to lead on the signal, hoping they are making eye contact with you and realizing they should call the net. If they don't pick up on your hint, lead the net signal. But blow the play dead quickly if your partner does not.

Ideally your umpire/R2 should make the net call, but if you see it, it's ok to blow the whistle on that particular call.