In the rich text editor:
@boombycilla
In a comment:
[boombycilla](https://chowlings.com/user/boombycilla)
For Names and Avatars:
In the rich text editor:
%boombycilla
In a comment:
[](https://chowlings.com/user/boombycilla) [boombycilla](https://chowlings.com/user/boombycilla)