THE SCHEDULED FLT DEPD BETHEL, AK, WITH A WX DISPATCH RELEASE. WHEN THE FLT REACHED THE DESTN (CHEVAK, AK), THE STATION MANAGER (A NON-CERTIFIED WX OBSERVER) ADZD THE FLT CREW TO NOT ATTEMPT A LNDG, BECAUSE THE WX WAS NOT GOOD. ACCORDING TO THE FLT CREW, HOWEVER, THE FOG WAS NOT OBSCURING THE RWY & THEY ELECTED TO MAKE AN APCH. ACCORDING TO THE PILOT (PIC), A HIGH SINK RATED DEVELOPED ON SHORT FINAL & HE DID NOT APPLY POWER. HE BELIEVED THE LNDG FLARE WOULD HAVE ARREST THE SINK RATE. HOWEVER, THE ACFT LNDD HARD ON THE RGT MAIN GEAR, CAUSING IT TO SEP & DMG THE RGT MAIN WING STRUT. THE RGT WING SETTLED TO THE SURFACE & THE ACFT YAWED TO THE RGT, VEERED OFF THE RWY & WAS FURTHER DMGD. THE LOAD MANIFEST DID NOT COMPLY WITH 14 CFR PART 135.63(C) OR THE COMPANY'S OPERATIONS MANUAL.