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