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