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