Select a number of existing rows, then go to the Table Tools > Layout tab of the
ribbon and click either Insert Above or Insert Below. An equal number of rows
will be added above or below the selected ones.

If you want to use a macro, this one will add as many rows as you tell it to,
even if it's more than already exist (see
http://www.gmayor.com/installing_macro.htm if needed):

Sub AddRowsToEnd()
   Dim strRows As String
   Dim nRows As Long, i As Long
   Dim Tbl As Table
   
   If Not Selection.Information(wdWithInTable) _
       Then Exit Sub
   
   strRows = InputBox("Number of rows to add", _
           "Add rows to end of table")
   If Len(strRows) = 0 Then Exit Sub ' canceled
   
   nRows = Val(strRows)
   If nRows > 0 Then
       Set Tbl = Selection.Tables(1)
       For i = 1 To nRows
           Tbl.Rows.Add
       Next
       Set Tbl = Nothing
   End If
End Sub

--
Regards,
Jay Freedman
Microsoft Word MVP        FAQ: http://word.mvps.org
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