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