Hi Bee,
The acf/render_field action will add the script when the field is rendered while the acf/input/admin_footer will add the script in the footer. It really depends on how you want it to be, but the best place to add JS script is in the footer (the bottom of your page). This page should give you more idea about it: http://stackoverflow.com/questions/5329807/benefits-of-loading-js-at-the-bottom-as-opposed-to-the-top-of-the-document.
I hope this makes sense 🙂
