Tremendo aporte, lo acabo de usar y está excelente, lo dejé así:
This.AddObject("owb","oleControl","Shell.Explorer.2")
This.oWb.Top = 0
This.oWb.Left = 0
This.oWb.Width = Thisform.Width
This.oWb.Height = Thisform.Height
This.oWb.Visible = .T.
This.oWb.Anchor = 240
This.AddProperty("cPDFFileName","")
This.AddProperty("nPdfLoadTimeout",30)
* Get PDF file name
Thisform.cPdfFileName = Getfile("pdf")
* Display the name in the textbox
This.Caption = Thisform.cPdfFileName
If Not Empty(Thisform.cPdfFileName)
* Display PDF
Thisform.ShowPdf()
Endif
y obviamente agrego el método ShowPDF, de ahí todo va excelente!!!!