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