Rnić started out at his hometown club Proleter Zrenjanin. He was promoted to the senior squad in the 2004–05 season. In 2008, Rnić moved abroad to Slovenia and signed with Gorenje Velenje. He helped them win the championship title in his debut year. In 2010, Rnić was transferred to fellow Slovenian team Celje.
International career
Youth
At youth level, Rnić was a member of the Serbia and Montenegro winning squad at the 2004 European Under-18 Championship.[1] He subsequently helped his nation win the gold medal at the 2005 World Under-19 Championship.[2]