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