In QGIS 2.14, in print composer I can save my project as a PDF file. There is no controls of the color space in which colors are specified in the output file. It will be very useful to have a choice of the color space: RGB or CMYK. Is it possible to resolve this issue ?
QGIS uses the PDF output of the Qt toolkit which unfortunately has no way of setting the colour space. Indeed the Qt toolkit as a whole is 'colour space blind'. It would require a lot of work on the Qt toolkit to make this happen, and I know of no current efforts to do so.
A little more info is in this "CMYK implementation in QGIS?" thread on the QGIS developer list.