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