I am new to Mac but am seeking to design a brochure for printing using the Pages app. The normal color settings of RGB and CMYK do not seem to be present. What color setting do I need to use to obtain a CMYK "true black"?
Pages simply isn't designed for professional commercial printing. If you need to control your output for commercial offset printing you're better off using something like Adobe Illustrator or InDesign. If you're printing the brochure yourself or using a digital printing service then you may be better off working in RGB and letting the printer do the conversion for you.
You can choose CMYK colors by changing to CMYK Sliders in the Colors dialog. You can also choose a specific color profile by cliking the cog to the right of the slider:
It seems this is a per-object setting though, not per document.
The default PDF export however will always output an RGB PDF, which will in turn convert your colors back to RGB. If you have Acrobat installed you can export a CMYK Adobe PDF by instead going to Print and selecting "Save as Adobe PDF" from the PDF dropdown (bottom left of the dialog). You can then select a preset with the correct color profile and output settings...
But, I cannot in any way with any settings get the PDF to output with the correct CMYK values—Pages always converts your colors somewhere in the process.
The only other option is to use something like Adobe Acrobat to convert your colors after exporting your PDF (using either Preflight or the Convert Colors tool).