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