Rotate text itext sharp rectangle C#

Need rotate text for 90'

On page have text but I cant rotate

Some help?  

iTextSharp.text.Rectangle prevoznik = new iTextSharp.text.Rectangle(340f, 210f, 160f, 50f, 90);  
ColumnText ct = new ColumnText(cb);  
ct.SetSimpleColumn(prevoznik);  
 ct.AddElement(new Paragraph("Probni tekst. ", calibri2));  
ct.Go();