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