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