How can I change the line-height of a PDF font or paragraph using iTextSharp?
Line spacing in terms of typography is called leading. If you can use line spacing, you can use Paragraph.Leading or Paragraph.LeadingMultiplier. See http://itextsharp.sourceforge.net/tutorial/ch02.html#phrase
paragraph.SetLeading(X, Y) where X - is fixed leading and Y is leading multiplayer. Leading is space between two text baselines. Final leading value is calculated like: X+Y*max font size in row.
Not sure in what context your text is in, but I have mine in a PdfCell and I used MinimumHeight and PaddingTop:
cAddr = new PdfPCell(ptAddr);
cAddr.MinimumHeight = 101.0F;
cAddr.PaddingTop = 30;
来源：https://stackoverflow.com/questions/2630430/how-to-set-pdf-paragraph-or-font-line-height-with-itextsharp