This sample shows how to use CMYK colors.
PDF Output File
See the PDF file created by this sample:
output.pdf (78 kB)
Screen Shots
Here is a sample screen shot:

Source Code
This is the source code the shows how to set the color mode to CMYK:
PdfDocument document = PdfReader.Open(filename);
document.Options.ColorMode = PdfColorMode.Cmyk;
// Set version to PDF 1.4 (Acrobat 5) because we use transparency.
if (document.Version < 14)
document.Version = 14;
PdfPage page = document.Pages[0];
// Get an XGraphics object for drawing beneath the existing content
XGraphics gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Append);
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(1, 0.68, 0, 0.12)), new XRect(30, 60, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0, 0.70, 1, 0)), new XRect(550, 60, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0, 0, 0, 0)), new XRect(90, 100, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0, 0, 0, 0)), new XRect(150, 100, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0.7, 0, 0.70, 1, 0)), new XRect(90, 100, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0.5, 0, 0.70, 1, 0)), new XRect(150, 100, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0.35, 0.15, 0, 0.08)), new XRect(50, 360, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0.25, 0.10, 0, 0.05)), new XRect(150, 360, 50, 50));
gfx.DrawRectangle(new XSolidBrush(XColor.FromCmyk(0.15, 0.05, 0, 0)), new XRect(250, 360, 50, 50));