ProRes only supports RGB and I444 and requires next to no additional setup, all you need to do is adjust the profile setting according to the table below:
|Effective Lossless||4444 Extreme Quality (AP4X)|
|Visually Lossless||4444 High Quality (AP4H)|
|High Quality||422 High Quality (APCH)|
|Acceptable Quality||422 Standard (APCN)|
Due to there being no further profiles to support 4:4:4 at lower quality, 4:2:2 subsampling is used. This halves the horizontal chroma samples, while keeping the vertical chroma samples in tact – not exactly ideal for text and other high contrast content.