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