Sub TestTable()
Dim dbs As DAO.Database
Dim tdf As DAO.TableDef
Dim fld As DAO.Field
Dim inx As DAO.Index
Dim i As Long
Dim avFields As Variant

Const TABLE_NAME$ = "MSysAccessStorage"
Set dbs = CurrentDb
Set tdf = dbs.TableDefs(TABLE_NAME)

    For Each inx In tdf.Indexes
        If inx.Primary Then
            avFields = Split(Replace(inx.Fields, "+", vbNullString), ";")
                For i = LBound(avFields) To UBound(avFields)
                    Set fld = tdf(avFields(i))
                        If fld.Attributes And dbAutoIncrField Then MsgBox "Поле " & fld.Name & " является счётчиком и" & IIf((UBound(avFields) - LBound(avFields)) > 0, " входит в состав ключа", " ключевым"): Exit For
                Next i
            Exit For
        End If
    Next inx
Set fld = Nothing
Set inx = Nothing
Set tdf = Nothing
Set dbs = Nothing
End Sub