My first question ever. I am considering buying the Panasonic Lumix GX85 and would like to know if I can use my Yongnuo YN968 EX-RT flash with it. Are they compatible? Will I get TTL with this combo? From down in Brazil... ofotografoamericano.
The Yongnuo 'RT' protocol is a clone of Canon's 'RT' system. Unless Panasonic also uses the Canon 'RT' procol (which is highly unlikely), you won't get radio based TTL using the YN968EX-RT with any camera other than a Canon.
Since the pin pattern on the hot foot of the YN968EX-RT matches the pattern on the hot shoes of Canon cameras, at best you would only be able to tell the flash to "fire" when it is mounted in a Panasonic hot shoe with a different pin pattern for all but the center pin.
In addition to Canon RT protocols, which are radio based, the YN968EX-RT can also receive both Canon and Nikon optical based wireless signals, according to this entry at Flash Havoc.