Let's embed a Kappa project in the Webflow page - 

1. Click share & embed.
2. Copy iframe code.
3. In the Webflow editor, press A to open the Add elements panel.
4. Add an embed element from the components section.
5. Paste in the custom code you copied.
6. Save and close the modal.

To add a Kappa project as a rich text element -

1. Place your cursor where you’d like to add custom code
2. Click the plus sign to open the insert menu and click the custom code button
3. Add your code

Follow this link to know more.