Are you meaning to know if a dot on a map is a certain user? If so, there already is a way to do this.
If that is what you mean- Just open your friends list (the double paws). Then click on a friend that is CURRENTLY online. Then you'll see a little options window pop on your game screen. You'll notice one of them says 'Find'. Click that. If the dot blinks/lights up- then that's the username of the person you're trying to find.
However clicking on the dot definitely is an interesting idea. Quick access to figure out which friend it is~