This is the key that Kartris uses server-side to communicate with the Stripe servers. This will not be visible to the user's browser in any way during the process, and as such is "secret". It will generally start with the letters "sk_".
Ensure your page has the following code pasted near the bottom, before the closing 'body' tag.
Copy this code and place it where you want the help icon to appear in your page.
Your help link will appear as the icon below. Click it to verify how the help content will look.
Place a QR code on your product or machinery to let a user easily retrieve the user guide documentation for it.
Right-click and 'copy'