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