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