In view of the HL-LHC parameters, the present and the foreseen RF systems are reviewed with the primary focus on technological aspects. This paper will describe the preparation and the test program of the SPS beam tests with crab cavities. Some aspects related to the integration of the crab cavity RF system in the LHC and the potential impact of the crab kissing scheme are addressed. The mode of operation for the 400 MHz accelerating RF system with HL-LHC beam currents and the associated issues are briefly outlined with possible improvements to the ACS system. Finally, the use of a harmonic system both at 200 MHz and 800 MHz for bunch profile manipulation and the associated technological challenges are described.