In the rich text editor:
@Robgen
In a comment:
[Robgen](https://chowlings.com/user/Robgen)
For Names and Avatars:
In the rich text editor:
%Robgen
In a comment:
[![Robgen's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Robgen) [Robgen](https://chowlings.com/user/Robgen)