Question about a chess puzzle.

I did a puzzle on lichess but I can't figure out a particular move. On move 13, it says that the black Bishop should capture f2 and then it says that the Rook should capture f2 and not the king. I was trying to figure out why other than because the computer says so.

[pgn][Event "Rated game"] [Site "http://lichess.org/s9cfapiv"] [Date "2013.12.25"] [White "delusion18"] [Black "tiptop414"] [Result "1-0"] [WhiteElo "1442"] [BlackElo "1523"] [PlyCount "45"] [Variant "Standard"] [TimeControl "300+6"] [ECO "B20"] [Opening "Sicilian Defence, General"] [Termination "Normal"] [Annotator "lichess.org"]

1. e4 c5 { Sicilian Defence, General } 2. d4 e6?! { (0.00 → 0.62) Inaccuracy. The best move was cxd4. } (2... cxd4 3. Nf3 Nc6 4. Nxd4 e6 5. Be3 Nf6 6. Nc3) 3. dxc5 Bxc5 4. Nf3 d6 5. Nc3 Nf6 6. Bc4 Qb6 7. O-O Nbd7?! { (0.20 → 0.70) Inaccuracy. The best move was O-O. } (7... O-O 8. b3 Bd7 9. a3 Rfc8 10. Bg5 a5 11. Bxf6 gxf6 12. Qd3) 8. Bg5?! { (0.70 → 0.20) Inaccuracy. The best move was a3. } (8. a3 a5 9. Qe2 Qc7 10. Bb5 O-O 11. Be3 Bxe3 12. Qxe3 Ne5) 8... O-O 9. Bb5?! { (0.50 → -0.04) Inaccuracy. The best move was Na4. } (9. Na4 Qb4 10. Nxc5 Nxc5 11. Bxf6 gxf6 12. Qd4 b5 13. Bd3 Qxd4) 9... h6 10. Bxd7 hxg5 11. Bxc8 Raxc8 12. Nxg5?! { (-0.82 → -1.39) Inaccuracy. The best move was Na4. } (12. Na4 Qb5 13. Nxc5 Rxc5 14. Qxd6 Nxe4 15. Qd3 g4 16. Qxe4 gxf3) 12... Qxb2 13. Qd3?? { (-1.35 → -6.16) Blunder. The best move was Na4. } (13. Na4 Qb5 14. Nxc5 Rxc5 15. h4 Qc6 16. Rfe1 Rxc2 17. Rac1 Rxc1) 13... Bxf2+ 14. Kxf2? { (-5.85 → -7.93) Mistake. The best move was Rxf2. } (14. Rxf2 Qxa1+ 15. Nd1 Qe5 16. Nf3 Qxe4 17. Ne3 Qxd3 18. cxd3 Rc1+) 14... Qxc3?? { (-7.93 → -3.23) Blunder. The best move was Rxc3. } (14... Rxc3 15. Rfb1 Qa3 16. Qb5 Rxc2+ 17. Kg1 Qe3+ 18. Kh1 Rc5 19. Qxb7) 15. Qxc3 Rxc3 16. Rac1 Rfc8 17. a4 Rc3xc2+ 18. Rxc2 Rxc2+ 19. Kg1 Ra2? { (-3.91 → -2.64) Mistake. The best move was Rc5. } (19... Rc5 20. h4 Kf8 21. Kf2 b6 22. Ke3 Rc3+ 23. Kd2 Ra3 24. Rc1) 20. Rb1 b6 21. Rb4? { (-3.05 → -4.48) Mistake. The best move was Rc1. } (21. Rc1 Ne8 22. Rc8 Kf8 23. Rb8 Rc2 24. Ra8 Rc7 25. Kf2 Ke7) 21... a5? { (-4.48 → -1.61) Mistake. The best move was Ng4. } (21... Ng4 22. Rb1 Rxa4 23. h3 Ne5 24. Rd1 Kf8 25. Rxd6 Ke7 26. Rd2) 22. Rxb6 Rxa4?? { (-1.55 → Mate in 2) Checkmate is now unavoidable. The best move was Nh7. } (22... Nh7 23. Nxh7 Kxh7 24. Rxd6 Rxa4 25. Ra6 Rxe4 26. Rxa5 Re2 27. h4) 23. Rb8+ { Black resigns } 1-0[/pgn]