I was able to get an answer this afternoon from an SPS tech who said the unit I got will not work. It did say that on their webpage, but since when do we believe what we read?!? The RL apparently requires a similar shift knob to the L series, due to the lift reverse ring and there are very few aftermarket units available.
Additionally, it appears to be a real chore to remove the old knob. It is press-fit onto the shaft and according to the tech, requires breaking the knob off to get to a clean surface to mount the new knob. Yikes!
I love the car, but did the engineers make anything easy (oil change, air filter replacement, etc.) for the do-it-yourselfer?!? He suggested a MOMO unit, but it's significantly higher in cost and not particularly the look I'm after. I'll have to think about it a bit more. Maybe I just need to begin liking the look of the present knob!