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