After you've created a Content skill and added a thumbnail, you can add a Form
To add an external link, click on Link
Enter the link title
Enter the link description (optional)
Enter the URL. This could be a link to a YouTube video, your LMS, or a company site. To link to a PDF, upload it to Google Drive / Dropbox and enter the URL.
Enter Button Title for e.g Find out More, Click Here, Start Now etc
Click Close
