RSF

• Religious Society of Friends, a Christian religious group, the Quakers
• Reporters Without Borders (RSF; {{langx|fr|link=no|Reporters Sans Frontières}})
• Republican Sinn Féin, a small political party in Ireland
• Road Safety Foundation in the UK and Ireland
• Russell Sage Foundation, a philanthropic foundation and publisher

• Russian Socialist Federation of the Socialist Party of America

• Racing Steps Foundation, a UK motorsports support organization
• Roar Supporters Federation, a fan association for Brisbane Roar FC, Brisbane, Queensland, Australia

• Rapid Support Forces, paramilitary forces formerly operated by the government of Sudan
• Ranger Strike Forces, Kenya Special Forces
• Regiment Special Force, Sri Lankan Air Force; an elite unit
• Reserve Strike Force, I Corps (Sri Lanka); a rapid reaction force
• Rhodesian Security Forces, the military and security forces of the government of former Rhodesia (1964–1980)
• Royal Scots Fusiliers, former line infantry regiment of the British Army (1678–1959)
• Rwandan Security Forces, part of the Rwanda Defence Force

• Republican Security Forces, a fictional fascist militia in the British science fiction series Doctor Who

• Rainbow Serpent Festival, an arts, music and lifestyle festival in Victoria, Australia
• Referee stopped fight, in boxing
• Right Said Fred, British music band
• Royal straight flush, a hand in poker
• RSF, a French synthesizer manufacturer. See RSF Kobol for an example.

• Rancho Santa Fe, a settlement in California, USA
• Recovery Support Function, a component of the National Disaster Recovery Framework (NDRF)

• Rentable Square Feet, a measure of floor area (building)
• Resource selection function, in ecology
• RSF: The Russell Sage Foundation Journal of the Social Sciences

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• {{srt}}

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