here's an old thread with some pix of my galley zone...
ZOOM the 3rd pic in post #2 and the spice rack can be seen installed behind the range top.
since it's NOT heavy and hard to OVER load i think it's just screwed right into the inner skin...
without regard for the ribs.
i also don't think any holes where drilled as the screws are standard a/s metal/wood screws...
((look around at ANY of the interior trim installed with screws, metal OR wood trim the screws are ALL the same))
((a/s uses THESE for just about everything in different lengths and painted tan/white with PHILLIPS heads))
one could also use AUTOMOTIVE grade double stick exterior TRIM tape (3m) and that should hold nicely for years...
ribs are WHEREever vertical rivet lines are on the outside and pretty easy to locate.
there is also a FLAT bottom/counter top version of the spice rack (with tambour door) which can be seen in post # 14 (link above)
this is a more substantial rack that's deeper, heavier and holds more. (and is still available in the a/s parts store)