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