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