Brunner, O. Schwerg, N. JACoW Geneva, Switzerland The FCC-ee RF system must handle beams at different energies and beam intensities ranging from the high energy case of a few mA at 175 GeV to the heavily beam loaded situation at 1.45 A and 45.5 GeV. Higher order mode power will be a major issue at the highest beam intensities. A conceptual design of the FCC RF system is proposed along with highlights of specific R&D topics to reach the design performance. Challenges related to RF structure design, RF powering and higher order modes are addressed. Breakeven point between bulk Nb and Nb/Cu technologies are discussed.