RSO guarantees one of each resource in the starting area. I thought that was default behavior too, but I guess not. The patches do tend to be a bit big; in my first game with a rocket launch I only needed to expand to one each of iron and copper fields, and two new oil fields to get what I needed. My current game is generated with small patches & many aliens, to make expansion both more necessary and harder.
Have some images from this game:
Full expansion:
Local View:
Right now, my expansion is throttled a bit by the ore. I wanted to move the railstations near my base up a ways to make room for multiple stations of each kind, and so I can run at least two tracks in each direction.
Lab complex:
I wound up moving the labs three times.
Full Map:
I completely lost track of actually launching the rocket in this game. I think I might just give it up anyways and try one of the more expansive mod sets like Bob's Mod + Dytech.