Scripture IS the final/sole authority for the Christian faith. When God says it, it's final. Your RCC doesn't speak with the authority of God. It only speaks as the self-appointed ecclesiastical authority created by men.
Matthew 4: 4 Jesus answered, “It is written: ‘Man shall not live on bread alone, but on every word that comes from the mouth of God.”
John 16:13 "But when he, the Spirit of truth, comes, he will guide you into all the truth. He will not speak on his own; he will speak only what he hears, and he will tell you what is yet to come."
2 Timothy 3: 16 "All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17 so that the servant of God[a] may be thoroughly equipped for every good work."
Since Scripture is useful for teaching, rebuking, correcting and training in righteousness what more do we need. Nothing.