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