Sideline OOB (Step or Dribble OOB) Mechanic??

[Woodee]

What is the proper mechanic for signalling a sideline OOB play when the player steps or dribbles OOB? Especially when you are a distance away from the play. An errant pass OOB is easy to see but a dribble or step on the line isn't.

I whistle, point to the line and the direction. I keep getting the WHAT happened looks??? Should I close in and point? Verbally say OOB? What do you folks do?