mORMot Open Source

I have a QRComposite report and exporting it to pdf by QRSynPDFDocumentFilter.
The output looks nice, but it has A4 size. My report has A3, but the pdf cuts only an A4 piece from it.

I am using this code :

Procedure TForm1.ConvertToPdf(MyRep:TQRCompositeReport; RepFileName:String);
var
    spdf : TQRSynPDFDocumentFilter;
begin

      spdf := TQRSynPDFDocumentFilter.Create('D:\'+RepFileName+'.pdf');
      spdf.HideMenubar := true;
      spdf.CompressionOn := true;
      spdf.HideToolbar := true;
      spdf.FontHandling := AutoEmbed;
      spdf.SetPageParams();
      MyRep.ExportToFilter(spdf);
      spdf.Free;
end;

QRSynPDFDocumentFilter does not have an defaultpagesize wich I can set.
How can I set the page size ?
Is this problem because it is an CompositeReport ?
At the begining I tried to export it to PDF using PdfDocumentGDI, but I did not knew how to acces the metafile for a composite report (So I did not had succes).
The filter is working, but I have the pagesize problem - always A4.

Thank you in advance for your help !
Toni