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