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