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