How to creat Copy button to my Vantage Website?

Dear SiteOrigin Creators!

Could you help me? I would like to creat a Copy button (Copy to clipboard) to my Vantage website…
I need the Copy button because I use full Copy/Right click protection on my site, but I would like to use a Copy button only 1 page.

On the web, I found some Javascript examples, I tried the javascript source copy to my functions.php but not worked. :/

Thank you very much in advance!