This has been asked before, but I don't see any resolutions to the problem.
I created a page on RSD then submitted to ebay, but it would not upload as it contained java script.

I narrowed it down to this line:
<script src="js/picturefill.min.js" class="picturefill" async="async"></script>

Deleting the line from the code allows it to be uploaded, but the result is not good looking or responsive.
The code means nothing to me, but is there an alternative I could include that might be ebay friendly?

Try including the entire script within the head of the page.