C#:

//Create a new pdf document

PdfDocument document = new PdfDocument();

//Add the page

PdfPage page = document.Pages.Add();

//Save the current graphics states

PdfGraphicsState state = page.Graphics.Save();

//Translate the coordinate system’s to where you want to draw the text position

page.Graphics.TranslateTransform(100, 100);

//Rotate the coordinate system’s

page.Graphics.RotateTransform(90);

//Draw the string at the origin

page.Graphics.DrawString("Text rotation", new PdfStandardFont(PdfFontFamily.Courier,20), PdfBrushes.DarkBlue, new PointF(0, 0));

//Restore the graphics state

page.Graphics.Restore(state);

//Save and close the document

document.Save("Output.pdf");

document.Close(true);