The Thinking Asexual has a lot of good blog posts, and much of what is written about how asexuals experience relationships is relevant to RA, particularly in regards to not elevating one type of relationship above another. This blog post offers an overview, lots of definitions and examples, and an explanation of how RA applies to asexuals, aromantics, mixed orientation sexual people, and celibates.
The Thinking Asexual three types of non-monogamy: hierarchical polyamory, non-hierarchical polyamory and relationship anarchy. The differences between non-hierarchical poly and RA can be a confusing, this post goes over some of the reasons they are different. It also delves into how an RA might view non-romantic / nonsexual friendships.