Use Adobe Media Encoder for H.264 encoding. It has Vimeo encoding presets. Do not use the H.264 codec in a QuickTime container.
Thank you Todd. The only other problem I'm having is that I'm seeing banding in my exported movie. I even tried exporting as Pro Res and Animation codecs, and I'm still seeing banding:
Do you what I could do to get rid of the banding? I set the bit rate to 20 Mbps thinking that would be more than sufficient to have a clean looking animated film on Vimeo, but there's still banding present.
Banding is a constant bane of web and video designers. The issue with banding comes with compression and the limited color space of RGB. The solution is to introduce some noise to the image. A 50% grey solid layer with the noise effect cranked to 100 and opacity set to 2-5% usually does the trick. Noise is expected in video, since film grain has been around since film began.
Before reading your reply I actually duplicated the layer last night and applied a 30% noise filter to the top layer and set it to "Darken" blend mode. Noise was quite pleasant actually. But for some reason noise doesn't show up on export, though it did greatly diminish the banding almost to the point of none being visible.
I'll try your settings as well. Thanks again for your help.