In the rich text editor:
@LarrsonMarrson
In a comment:
[LarrsonMarrson](https://chowlings.com/user/LarrsonMarrson)
For Names and Avatars:
In the rich text editor:
%LarrsonMarrson
In a comment:
[![LarrsonMarrson's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/LarrsonMarrson) [LarrsonMarrson](https://chowlings.com/user/LarrsonMarrson)