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