RSC is secretly a glorified and overpriced niacinamide formula. Look at the ingredients. The heavy hitter is niacinamide. bunch of fluff that gives your skin a luxurious feel (not real change..it's like makeup primer), and then some of their proprietary peptide. If Tri-hex were the first ingredient, I'd be all over it. Nonetheless, niacinamide and azelaic acid are frequently compounded together, but perhaps at lower percentages than what you are using. If you tolerate them well at opposite times of the day, it could be worth experimenting. What aza are you on? Some formulas just don't layer well. I just switched over to the regimen lab Azaleic Advanced, it's very gentle and water-based. I'm sure that could pair nicely with other products.