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