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