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