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