define page size

i use the code below to print a PDF...for some reason the page size is coming out as 11.81X15.28...is there a way to define the page size as 8.5x11?

  PdfFile = ActiveWorkbook.FullName
  i = InStrRev(PdfFile, "CURRENT PROJECTS")
  If i > 1 Then PdfFile = Left(PdfFile, i - 1)
  PdfFile = "CURRENT PROJECTS" & ".pdf"
 
  ' Export activesheet as PDF
    Worksheets("ACTIVE PROJECTS").Range("B3:H175").ExportAsFixedFormat _
     Type:=xlTypePDF, Filename:="S:\" & PdfFile, Quality:=xlQualityStandard, _
      IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:=True
  Shell "cmd /S " & """" & PdfFile & """", vbNormal