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