The best way depends on what you're trying to achieve. Also depending on their impedance they can be wired in series or in parallel regardless of how many speaker outs the amp has. You just need to pay attention to and avoid too low impedance for the amp.
First of all, since you say this is for music, then the best way is to use the best speakers and use whichever ones you don't prefer somewhere else. Because multiple speakers is going to ruin imaging and create as many problems as you imagine they solve.
That said, here are two different ones to try.
For the best imaging- position the 7s where you want them and stack one rf3 on top of each, only upside down.
For the best bass- position the 7s for stereo and place one 3 in each corner and facing the wall. Disconnect the tweeters, if possible, and if not then cover them. This will preserve imaging while greatly improving bass response.
A distant third would be side by side. This will create a "wall of sound" effect nice and loud and full but awful.
As far as newer receivers go, avoid them. Receivers, I mean. New or old, does not matter. Receivers are the bottom of the audio barrel. Only thing worse than a stereo receiver is a/v receiver.
First of all, since you say this is for music, then the best way is to use the best speakers and use whichever ones you don't prefer somewhere else. Because multiple speakers is going to ruin imaging and create as many problems as you imagine they solve.
That said, here are two different ones to try.
For the best imaging- position the 7s where you want them and stack one rf3 on top of each, only upside down.
For the best bass- position the 7s for stereo and place one 3 in each corner and facing the wall. Disconnect the tweeters, if possible, and if not then cover them. This will preserve imaging while greatly improving bass response.
A distant third would be side by side. This will create a "wall of sound" effect nice and loud and full but awful.
As far as newer receivers go, avoid them. Receivers, I mean. New or old, does not matter. Receivers are the bottom of the audio barrel. Only thing worse than a stereo receiver is a/v receiver.