I would suggest you start using it directly over your spine as well as using it on hands and feet. I find that using it on my spine has a beneficial effect all up and down the spine, which usually radiates out to my extremities, which I presume is the result of a general reduction in spinal inflammation. In your case the problem appears in your hands and feet, so if it is a spinal problem, it is more likely to be overall spinal inflammation (or something like that), but not a focal, localized injury in my opinion.
There will be no secret or special frequency (that kind of stuff is just PEMF marketer fraud). You should just start with the default settings (Omni-8 and intensity = 9), then maybe alternate every 3-4 days with Alpha Wave or Schumann 4, on intensity 9 or 10 or 11. These seem to generally work for people with spinal issues/inflammation. Be aware though that more power is not necessary, and often people get better results with intensity in the range of 9 - 11 than they do if they use higher intensity.
You could just stack the coils (bumpy-side to bumpy-side), then place them over a few different spots along your spine, just to see what works best for you. Give it 3 or 4 days before changing coil location or pulse pattern or intensity. I would start with placing the coils on your lower back, but then eventually try mid-back, then hands and feet, etc., to see what works best for you.
You will want to use it for 6 to 8 hours per day, every day. You might detect a benefit very soon (hours), or it may take 2 to 3 weeks. Everyone responds differently. This probably will not be a quick fix.
Please be sure to report back to the forum with your results, positive or negative, just your honest observations.