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