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