iTextSharp output pdf Gridview width used 100% of the page

I used the iTextsharp to output Gridview to pdf
My GV is only 30% of page width while the GV in pdf output is 100% of the width.
How can I control to retain the 30% width in pdf output ?
My code is
Dim htmlparser As New HTMLWorker(pdfDoc)
I found people saying HTMLWorker is obsolete already and should be changed to XMLWorker.
So how should I modify the code ?
Also I found the new itextsharp ddl has changed so the outputted GV has lost all the color and formatting.
What can we do ?
Pls help, thanks