In the rich text editor:
@Sporker
In a comment:
[Sporker](https://chowlings.com/user/Sporker)
For Names and Avatars:
In the rich text editor:
%Sporker
In a comment:
[![Sporker's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Sporker) [Sporker](https://chowlings.com/user/Sporker)