Render Google Recaptcha from external website

Someone know how can I render a google recaptcha from a external website?

If I just use the 'data-sitekey' from a external source I get the owner permission error.

Any ideia what I need to do it work?

I tried to request with curl the "/recaptcha/api2/anchor" and change the host in "recaptcha.anchor.Main.init" function, I can display display the recaptcha widget, but don't work yet.

I take a look into "neuroradiology/InsideReCaptcha" github but it appear to be old.

Someone have some tip?