How should player call for warning if TD is not watching?

How should a blitz player call for a warning if a TD is not watching?

I understand the USCF blitz rules to say that if a player’s opponent uses two hands to capture a piece, then the player can call on the TD to warn the opponent, and if it happens again the player can get a minute added to his time.

If a TD is not watching, and supposing the game has witnesses or is being videotaped, how should the player proceed?

May the player stop the clocks and call for a TD?

Thanks!

Yes