PDFsharp Line Break

Have you tried the XTextFormatter class?

See here:
http://www.pdfsharp.net/wiki/TextLayout-sample.ashx

Code snippet:

PdfDocument document = new PdfDocument();

PdfPage page = document.AddPage();
XGraphics gfx = XGraphics.FromPdfPage(page);
XFont font = new XFont("Times New Roman", 10, XFontStyle.Bold);
XTextFormatter tf = new XTextFormatter(gfx);

XRect rect = new XRect(40, 100, 250, 220);
gfx.DrawRectangle(XBrushes.SeaShell, rect);
tf.DrawString(text, font, XBrushes.Black, rect, XStringFormats.TopLeft);