What Roman Catholic doctrines are based only in the 7 books canonized by the Roman church, but not accepted by Protestants. (e.g., Tobit, Judith, Maccabees, the additions to Daniel and Esther, etc...)
There's a few notions, but no doctrine, as the domain of doctrine in the Catholic Church is encompassed entirely by the New Testament insofar as it is the fulfillment of the entire Old Testament.
But, here's a sampling off the top of my head:
Concerning the state of purgatory and Maccabees, Protestants wholly reject purgatory and they do so because they say it's only in Maccabees, which they also reject. But when Jesus says in His parable about repayment to the last penny, that also informs the Catholic understanding of what purgatory is.