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