The first era of Rogers drums is equipped with Swivomatic hardware. These are configured with machined parts and employ hex rods (with a few exceptions here and there). The early drums have flat grey paint inside and the last ones have speckled paint inside. All have rectangular paper labels inside that can almost always be viewed through the vent hole in the shell. They indicate either Cleveland, Dayton or Fullerton Ohio, though the last ones have small tags simply labeled Rogers 9/72. All these drums have interior reinforcing rings for the shells.
The next generation has Memri-Loc hardware. Typically that hardware is tubular metal and much larger. It also has devices to lock the hardware in place using a drum key. The early ones have speckled interiors, but eventually natural finish (as I recall). I'm less sure, but as time moved on, I believe the interior reinforcing rings were dropped during this era. Cymbal stands, pedal and high-hats are all considerably heavier.
Beyond those eras, you begin to see the signs of the drums being manufactured outside the US and they become similar to other off-shore products in look and feel.
Check out the information in the link at the upper right-hand corner of this website for the Vintage Drum Guide and the Rogers catalogs, in particular. Those should help with identification if the drums were built no later than the late 70's.