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