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