In the rich text editor:
@stubbornbun
In a comment:
[stubbornbun](https://chowlings.com/user/stubbornbun)
For Names and Avatars:
In the rich text editor:
%stubbornbun
In a comment:
[](https://chowlings.com/user/stubbornbun) [stubbornbun](https://chowlings.com/user/stubbornbun)