Pick your starting point

Find the row closest to what you're building and start from that template.

You're building	Real examples	Start from	Status
Light single engine, skids	Bell 206 / OH-58, UH-1, AS350, MD 500	UH-1H prefab, Light single on skids	Flown and tested
Medium/heavy twin, wheels	UH-60, Mi-8/17, Puma, NH90, AW139	Mi-8 prefab, Medium twin on wheels	Flown and tested
Tandem rotors	CH-47, CH-46	Mi-8 prefab as a base, Tandem rotor	Built and flown (H-47 conversion, not released yet)
Coaxial rotors	Ka-27/29/32, Ka-50/52	Mi-8 prefab as a base, Coaxial rotor	Can be described, not flight-tested yet
Fenestron, compound, gyroplane, intermeshing	EC135, X3, Cavalon, K-MAX	Other layouts	Partly possible, see the notes
Tilt-rotor, NOTAR	V-22, AW609, MD 520N	Other layouts	Not supported

"Can be described, not flight-tested yet" means RFM has every piece you'd need (multiple lift rotors, any control mixing, counter-rotation, multiple engines), but nobody's actually flown one yet. Expect to spend some time sorting out control signs and tuning, and give Known limitations a read first.

You can mix templates too. A single engine aircraft on wheels can use the Huey's topology with the Mi-8's wheel gear, no problem.