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