The Reti needs a lot of theory memorization, because it's highly transpositional.
It also needs a fir good bit of positional understanding, because white has a lot of plans to choose, regarding his central pawn structure.
In general, I wouldn't recommend playing this as white, unless you are an experienced player.
I have been studying through the Reti Opening from the book Starting Out: The Reti. I have enjoyed playing through positional masterpieces and learning the opening more completely. I am concerned over the fact that Neil Mcdonald says the he tried to keep theory to a minimum in the book. Is there theory, and long variations that are needed to be memorized, or can one easily get by in the Reti with a solid understanding of the resulting positions? Thanks.
This is just one of the games from the book, I found it inspiring.