Sub aTest()
  Dim r As Range
  If ActiveDocument.Bookmarks.Exists("SymbolAst") Then
    Set r = ActiveDocument.Bookmarks("SymbolAst").Range
    r.Collapse Direction:=wdCollapseStart
    ActiveDocument.Footnotes.Add Range:=r, Text:="This is a test", Reference:="*"
  Else
    MsgBox "Nope"
  End If
End Sub