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