Ratkovica started playing basketball for KK Drvomarket.[1]
He made his professional debut for KK Atlas (then called Beopetrol) during the 2002–03 season. In the following season, Ratkovica made his debut in the ULEB Cup.[2] For the 2004–05 season he was loaned to Avala Ada.[3]
After four years in Germany, Ratkovica signed a two-year contract with the Turkish club Aliağa Petkim. Ratkovica started the 2012–13 season with Aliağa Petkim, but he left the club after some matches and signed a one-year contract with Olin Edirne Basket.
In February 2013, he returned to Germany and signed with Artland Dragons for the rest of the season. The 2013–14 season Ratkovica started in Politekhnika-Halychyna, but after two games he left the club[5] and signed for the rest of the season with Walter Tigers Tübingen.[6] He also played there the 2014–15 season, where he was the League's assists leader.[7] During the 2014–15 season, Ratkovica averaged 9.6 points, 2.8 rebounds and 7.2 assists.