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