VBA to add the contents of an adjacent variable column size

Hi Guys

What I am looking to do is add up the contents of column F as far as the entry in Column A is the same and put answer in Column I where the entries in Columns A changes. The number of rows change for each group as different Stocks are entered.
I hope this makes sense. I hate having to make up titles. I have attached a workbook.

Thanks a lot in advance.
Mark