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