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