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Basically no matter if you put UHD 4K (3840x2160) or whatever resolution you want to export your sequence within a 4096x2160 (DCI 4K) container. Fairly trivial to do via Adobe Media Encoder or...

I take it you've never made a DCP before :)

Seriously though. When trying to squeak out the most visual quality in encoding to more "cinema minded" formats you need to have quality source...

You'll want to export a 16 bit DPX or TIF sequence in either sRGB or REC.709 in a DCI 4K wrapper (4096x2160). Then import and attach the stereo audio file.