In the rich text editor:
@The_SodaShark
In a comment:
[The_SodaShark](https://chowlings.com/user/The_SodaShark)
For Names and Avatars:
In the rich text editor:
%The_SodaShark
In a comment:
[](https://chowlings.com/user/The_SodaShark) [The_SodaShark](https://chowlings.com/user/The_SodaShark)