In my <Product> I have:
<WixVariable Id="WixUILicenseRtf" Value="LICENSE.rtf" />
LICENSE.rtf exists, and is an rtf file (I've tried saving with a few different programs in case it was a problem with one of them).
The file contains text (a whole license!), and the text is sensibly formatted.
Why then, is the License field of my installer blank?
It turns out you basically must generate your rtf with Wordpad, or make a perfect replica. Since mine are generated by scripts, I adjusted my script to insert the Wordpad header to the rtf file, and this fixed it.
来源：https://stackoverflow.com/questions/11364935/why-is-my-license-not-showing-up