You will need to create a new "iframe" widget in Carrd, and set it's URL to a specially-formatted PKfronters URL.

Here's a little form to help you generate the right URL:

Embedding PKfronters in Carrd doesn't use the "standard" method of embedding PKfronters - instead, it puts the main PKfronters app (the one that you can copy links to) in a mode that disables the normal user interface. This is done with the ?noui query parameter, which must be located before the URL hash containing your system ID.

If you have an existing PKfronters link - for example, in your Discord bio - and it displays how you want it to show on your Carrd, simply add ?noui before the #!, and paste that link into a Carrd iframe widget.

Feel free to ask in the #community-resources-help channel of the PluralKit support Discord server!