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