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