add HTML to header

Hi,
the survey options at the moment only allow to set og:title and og:description via the survey options. This is used for instance by Facebook.

We would like to add also og:image, e.g.:

property="og:image"
content="https://oslopsych.az1.qualtrics.com/WRQualtricsControlPanel/Graphic.php?IM=IM_7VqUCEHglkr4D41"
/>

However, I failed to add this HTML to the header. I thought it would work through the header in Look and Feel, but that doesn't work. I also tried to use add this meta html through a simple descriptive text edited in html, but that also failed. Either it doesn't come through, or facebook only looks into the HEAD to find those meta tags.

Any ideas how to get this additional meta tag into the html head section?

alternative, this could become a feature request to qualtrics: Please add a og:image to the survey options!
best, thomas