Sklansky on Razz
I don't have my copy any more and it's been a long time since I read it.
To me the key concept Sklansky pushed in that pamphlet was more the kind of thing you'd have expected from Caro rather than Sklansky. Back in those days Sklansky represented a mathematical approach to the game and Caro represented a psychological approach to the game. In Sklansky on Razz he preached the normal edict of Just Play Tight, but he grounded that in the idea that you should play tight from the point of view of the opponent. The strength of your hand comes from your upcards, from the range that an opponent would put you on. If you played tight with respect to the cards your opponent could see, and aggresviely represented nut cards as your downcards, then the opponent would tend to put you on very strong hands. Your downcards almost didn't matter.
Of course you could take that too far, but as a general guiding rule it's a powerful concept. Represent the hand that your opponents will fear. It's not just a Razz concept, it's a poker concept. For example, in hold'em if you raise pre-flop your opponents will almost always put you on AK and you can play accordingly on later streets.
Focus on what your opponents know about your hand and how that influences their thinking. That's the lesson from Sklansky on Razz
An old post at Anything But Hold Em points to an old 2+2 thread that questions whether Sklansky on Razz is outdated. If you think the book is about Razz then I guess maybe it is outdated. Games with both a forced bring-in and a forced raise were common back then (low card bring-in, high card then had a forced raise -- or the other way around, I don't remember which). That makes for a very different game.
But the book isn't really outdated. It's a book about poker, not a book about Razz.