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