In the rich text editor:
@golden-boy
In a comment:
[golden-boy](https://painted-relics.com/user/golden-boy)
For Names and Avatars:
In the rich text editor:
%golden-boy
In a comment:
[](https://painted-relics.com/user/golden-boy) [golden-boy](https://painted-relics.com/user/golden-boy)