In the rich text editor:
@MangoPotat
In a comment:
[MangoPotat](https://chowlings.com/user/MangoPotat)
For Names and Avatars:
In the rich text editor:
%MangoPotat
In a comment:
[](https://chowlings.com/user/MangoPotat) [MangoPotat](https://chowlings.com/user/MangoPotat)