Your proof is largely correct, but there are a number of minor things that need to be corrected, and in which the proof can be shortened quite a bit:
Lines 3 and 4: I am not sure about your rule, which looks like $\top I$ ... This should be $\land E$ or Simplification
Line 7: as we will see, there is no need to start a subproof here. And you already have this line on line 4. So this line can be removed
Line 8 can be removed as well
Line 9: again, no subproof necessary. Instead, get this statement from 1 and 4 through $\rightarrow E$, or Modus Ponens.
Line 11: first you need to isolate $Pa$ from 5 before you can get $\neg Ra$.
Line 12: again, first isolate $Ra$ by Simplication or $\land E$ from 5 before conjuncting $Ra$ and $\neg Ra$
... And line12 is your contradiction, hence your last line. So no more lines needed after this ... Which is why you don't need any of those subproofs.