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