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