Here's a little macro that will display an Input Box, where you can specify the number of rows to add. Add this to your Quick Access Toolbar or assign a keyboard shortcut for convenience. Please post again if you need help implementing this:
Sub InsertSeveralRowsBelow()
Dim NumberOfRows As Long
Message$ = "Enter the number of rows to add below the current selection."
Title$ = "Add Rows"
DefaultNum$ = "2"
NumberOfRows = InputBox(Message$, Title$, DefaultNum$)
Selection.InsertRowsBelow NumberOfRows
End Sub