In the rich text editor:
@Flashpaw
In a comment:
[Flashpaw](https://chowlings.com/user/Flashpaw)
For Names and Avatars:
In the rich text editor:
%Flashpaw
In a comment:
[![Flashpaw's Avatar](https://chowlings.com/images/avatars/1060.jpeg?v=1665266477)](https://chowlings.com/user/Flashpaw) [Flashpaw](https://chowlings.com/user/Flashpaw)