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