In the rich text editor:
@Fumi03
In a comment:
[Fumi03](https://chowlings.com/user/Fumi03)
For Names and Avatars:
In the rich text editor:
%Fumi03
In a comment:
[](https://chowlings.com/user/Fumi03) [Fumi03](https://chowlings.com/user/Fumi03)