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