In the rich text editor:
@321Amy123_ug
In a comment:
[321Amy123_ug](https://chowlings.com/user/321Amy123_ug)
For Names and Avatars:
In the rich text editor:
%321Amy123_ug
In a comment:
[](https://chowlings.com/user/321Amy123_ug) [321Amy123_ug](https://chowlings.com/user/321Amy123_ug)