Adding hook above featured image

Hi there,

I'm attempting to add an advertiser discloure hook to all my posts. But I want it to appear above my featured image. I've tried all the available hook locations (generate_before_content, etc.) and nothing quite gets it. It either appears in dead space above the container itself, or immediately after the featured image within the container.

How can I have it appear FIRST THING in the container, immediately before the featured image?

Thanks!