In the rich text editor:
@Newt
In a comment:
[Newt](https://chowlings.com/user/Newt)
For Names and Avatars:
In the rich text editor:
%Newt
In a comment:
[![Newt's Avatar](https://chowlings.com/images/avatars/4.png?v=1644063288)](https://chowlings.com/user/Newt) [Newt](https://chowlings.com/user/Newt)