How do I share my form on Facebook?

You can share your form to Facebook directly from the Form Editor by clicking Share → Social & URL → Share to Facebook. You will then be redirected to a draft post on Facebook, where you can add text and choose where your post is shared to.

After clicking "Share to Facebook" you will be directed to a draft Facebook post where you can add text and change sharing settings.

You can't embed the entire form so that it can be answered directly in the feed, but by sharing it as a URL, it's easy for your submitters to click the form and complete it.