In the rich text editor:
@Melon223
In a comment:
[Melon223](https://chowlings.com/user/Melon223)
For Names and Avatars:
In the rich text editor:
%Melon223
In a comment:
[![Melon223's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/Melon223) [Melon223](https://chowlings.com/user/Melon223)