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