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