I recently made a semi-fully working SFML + RakNet example on Github so other people can learn from example.
You can play as a rectangle and see other people (Who is automatically blue)
Other people will automatically disappear on leave or disappear after timeout and there's more functionality to it, too!
I hope this helps people looking for an example
https://github.com/vertchrite/SFML-RakNet-Example/blob/master/main.cpp
