Everyone here has named fantastic pedals for phasing.
I too own a Rhodes and am a huge fan of phasers. I have the complete set of Electro Harmonix Small Stones from the American versions from the 70's to the 80's versions of the Russian made ones.
My personal favorite is the American V4. The one right before they switched over to surface mount technology in the nano.
BUT out of all the V4's that I own, the best one would be the American V4 Analogman.
They don't make the V4's but they're easy to find. To find an Analogman American V4 is EVEN harder to find. There are better features on that also.
Regardless of the model, all of the small stones are easy to use, easy to setup, and are very butter creamy. I prefer the small stone with the color switch down.
The other phaser of choice would be the MXR Phase 90. I have both block and script versions both reissues. I prefer the Script version with the LED on it because it's more subtle than the block version of today.
I got info from
Classic Rhodes Effects, took their advice and went with it. I made a pretty good call on it and it turns out the way they're voiced, the Rhodes sounds fantastic through it. No matter when the Rhodes was made, either a 70's rhodes or a new 2009-2012 Rhodes, those pedals will sound great.