I am not sure of definitions about this.
It seem that Primary is defined as genetic and passed on through your genes. So your mother or father had it. Or your grand parents. This has been stated to be 70% of patients
Secondary seems to be too widely characterized as everything else including RLS triggered by food intolerance (triggers).
If you start with this division many people might think they are primary and there is less chance of relief.
In my case the RLS is certainly genetic. Mother, father sister, children. However mine is also triggered by food intolerance. This might mean that 70% of RLS patients have a chance of relief by adopting one of the diets I have mentioned ion other posts. The FODMAP diet and the Low Chemical diet.
Hence it might be possible that people with primary RLS are the main beneficiaries of a diet based approach to relief.
I am not suggesting that a diet is a cure. But if your RLS is triggered by something contained in certain foods and you then avoid those foods. No trigger no RLS equals a very happy patient with eyes wide open and a smile. It might be as simple as avoiding just one group of foods.
Let me know if you want more details of these diets.
I am just about symptom free after 50 years of severe RLS
Please note that I have just read recently about the 70% proportion of primary RLS and I don't know if its correct or what the primary source is.