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