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