Latest information is that the downed aircraft was an Su-24MK
Fencer, not an Su-22
Fitter.
Although a lucky shot with an RPG wouldn't be impossible, it's more likely that the aircraft was shot down by conventional AAA.
An interesting piece from Wikipedia:
A Libyan Su-22 crashed near the city of Benghazi, Libya on 23 February 2011. The crew members, Captain Attia Abdel Salem al Abdali and his number two, Ali Omar Gaddafi, were ordered to bomb the city in response to the 2011 Libyan protests. They refused, bailing out of the aircraft and parachuting to the ground. Su-22s also attacked Anti-Gaddafi positions on Ben Jawad in early March 2011 as government forces retook the town.