You want the adapters in the frame holes at the rear, there, just to the right of the upper red circle in the image. That's the balance point, or rather lifting there will raise the rear and put minimal weight on the front. I'd be hugely surprised if it was anything different on the R3R to the R3T in that respect. I just got a Becker-Technic stand that works like a center stand, it lifts on only those two points and the bike is balanced with the rear wheel in the air.
Lots of people have made blocks that have a pin on it, where the pin goes in the hole; there are images here of such setups. The blocks then rest on the rearmost arm of the bike lift and put most of the weight there.
Here are some - the pin goes into the hole, the flat metal part forms the lifting surface.
Lift | R3Owners
Personally, I've just spent myself out of that problem - I bought a German Kern-Stabi adapter plate. The ****ed thing cost a fortune, but it was the quickest and easiest way to get a superb lift adapter so I grinned and bore it.
It also hooks into those exakt frame holes, and I haven't seen any info anywhere that the R3 Roadster is any different to any other Rocket. The one thing to keep in mind is that newer Rockets have 9mm holes there, the older ones were 13mm or some such.