It is really impossible to "try" what you posted because what you posted doesn't compile.
Code:
Sub TestFonts()
Dim bUniformFont As Boolean
bUniformFont = True
With ActiveDocument.Range
If .Font.Name = "" Then
.InsertBefore "Check Font Name" & vbCr
bUniformFont = False
End If
If .Font.Size = 9999999 Then
.InsertBefore "Check Font Size" & vbCr
bUniformFont = False
End If
End With
If bUniformFont Then MsgBox "The font used in your document is uniform. E.g., same font name, same fault size throughout."
lbl_Exit:
Exit Sub
End Sub