RF would be radio frequencies below 1 gigahertz. It is more difficult to get printed circuits to work well at higher frequencies. A circuit tested and proven in wire-wrap may not work when implemented as a printed circuit. This becomes more true the higher one goes in frequency ranges. The applications are many.
Radar comes to mind for microwave, including radar jammers.
There are such companies. When I have worked on RF and on microwave layouts, I listened carefully to the electrical engineer and did what he wanted. There are engineers who mark their specialty in part by frequency ranges they work in. There are also many related printed circuit design topics to RF and microwave, such as cross talk, parasitics, reactance and controlled impedance, which are design problems that can affect non-RF circuits as well. Separate overlapping traces in order to diminish potential adjacent layer cross talk.