Is this RDM ?

Hello i have a question that i have not found in server rules.

When you are like 300 meters away from a guy and you want to take him down, but dont want to reveal yourself because maybe you get killed.

Is it then ok to text(cell phone) the person several times and tell him to drop his weapon or i will take action?

Is this RDM or is this fair play ? 

Please explain this you smart people

Well, unless you can identify him because he wears certain clothes and you met him before, you can't. You won't know who it is, so you won't know who to send the message to. You need to take the risk and get within shouting distance so you can actually tell him to drop the weapon. Or work in a team, you keep your scope aimed at him and send your friend to tell him to drop the gun.

Okey, so i need to remember names on people i see now also. thats just great.

Well thanks for the respond