You have to have your doctor to fill out an Rx form (provided by the vendor). Plus a certificate of medical necessity plus a patient information form. These are provided by the vendor (QAS, Raytel are two that I know of).
Some doctors are very resistant to allowing patients to self-test. I would test those waters first and query your doctor(s).
Then check with your insurance carrier to determine coverage for durable medical equipment (DME). Some insurance companies do not cover INR machines, saying it's more or less a "luxury," that you are certainly able to get to the doctor's office or lab. (Phooey!)
If your carrier does cover INR machines, ask if QAS or Raytel are in network.
You can pursue getting a tester through either of these 2 companies and they will handle all the paperwork for you and finding out how much your insurance company will pay.
Some insurance companies will cover test supplies, some will not.