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