According to the questions you raised in source code

[me-phistopheles]

In the comments at begin of SparkFunSi4703.h you raise the following questions:

If anyone manages to get this datasheet downloaded
http://wenku.baidu.com/view/d6f0e6ee5ef7ba0d4a733b61.html
Please let us know. It seem to be the latest version of the programming guide. It had a change on page 12 (write 0x8100 to 0x07)
that allowed me to get the chip working..

Also, if you happen to find "AN243: Using RDS/RBDS with the Si4701/03", please share. I love it when companies refer to
documents that don't exist.

The document at the baidu-page is for sure older, than the current document at the Skyworks site.
On the same page you can find the AN243 documentation

On this page you could get all the documentation Skyworks offers to this chip. Looks like, the new owner has done some restructuring to the better (at least for documentation)!