How to exporting a pdf with just the spot color?

[vegastar7]

I'm using a specialty ink for a print job, so I need to submit a separate pdf with just the spots where the special ink will be used. The pdf should just be one color, no CMYK. Apparently, the printer tells me my pdfs are all in CMYK even though I've converted the artwork to grayscale (and the artwork itself is black and white), and there are no CMYK channels. What do I need to do to export a pdf with just a spot color?

[Stephen Marsh]

Can you post a screenshot of your channels?

[rob day]

You can't export or save a PDF out of InDesign or Photoshop with only spot plates—CMYK plates are always included, but can be left blank.

Make sure your spot art is limited to a Spot Channel and you include Spot Colors in the Save dialog:

Saved as PDF/X:

[vegastar7]

I followed the steps above, but it doesn't look like the pdf will save the output preview settings. So the printer has to do that part, I assume?

[rob day]

The screen capture of the Output Preview panel is from AcrobatPro. Save your PDF using the PDF/X-1a preset and open in Acrobat, then Print Production>Output Preview.