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.
In the Episcopal Church in the USA, excerpts from the Apocrypha are read in services. But the Apocrypha is not a source for doctrine. We pray for the dead, as do Catholics around the World. This idea is confirmed in Macabees, and it has always been part of the Church Liturgy since the beginning.
In the examination for Holy Orders in the ACC it is required: §11.9.01 Holy Scripture: The Old and New Testaments with the Apocrypha in English, their contents, teachings, theology, and historical background;
The word "Apocrypha" originally meant "sacred books that were reserved for the wise." The Greek word has the meaning hidden i.e hidden from those who were not yet wise. The explanation is in 4 Esdras which, of course, you may not have seen if you follow Protestant doctrine.
From New Advent Catholic Encyclopedia (emphasis added):
Since all these books are in the Anglican, Orthodox, and Catholic Bibles (with some variation) they are indeed scripture, and all scripture is sacred. So it is proper in the "catholic" Church to refer to the books as "sacred."