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