Animation in a mobile screen skin

Hi guys, I am new to Principle, so pardon me for a simple question.

Is there an easy way to put the designs in mobile phone screen?

I have created a simple animation on my mobile screen prototypes, and then I realized I want them in the phone frame skin. I added that to the Sketch artboards to be imported to Principle, but Principle turns all the different Sketch layers into one image… This only happens with the artboards where I have the mobile skin. I even converted the skin to image, still the same result.

Thanks!

If you use masks in sketch when you import to principle will be flatten.