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