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