ExcelのシートにPDF

元の縦横比を維持するならば

With ActiveSheet.Shapes.AddOLEObject(Filename:="c:testtest.pdf")
.Left = 100
.Top = 100
.Width = 100
End With

や

With ActiveSheet.OLEObjects.Add(Filename:="c:testtest.pdf").ShapeRange
.Left = 100
.Top = 100
.Width = 100
End With

のようにして
Width もしくは Height を指定
維持しないならば

With ActiveSheet.Shapes.AddOLEObject(Filename:="c:testtest.pdf")
.Left = 100
.Top = 100
.LockAspectRatio = False
.Width = 100
.Height = 100
End With

や

With ActiveSheet.OLEObjects.Add(Filename:="c:testtest.pdf").ShapeRange
.Left = 100
.Top = 100
.LockAspectRatio = False
.Width = 100
.Height = 100
End With

や

With ActiveSheet.OLEObjects.Add(Filename:="c:testtest.pdf")
.Left = 100
.Top = 100
.Width = 100
.Height = 100
End With

2007 では Top と Left は引数に入れても良さそう．