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