In the rich text editor:
@marsillpost1
In a comment:
[marsillpost1](https://chowlings.com/user/marsillpost1)
For Names and Avatars:
In the rich text editor:
%marsillpost1
In a comment:
[![marsillpost1's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/marsillpost1) [marsillpost1](https://chowlings.com/user/marsillpost1)