The Information on foreign exchange rates are available in the Reserve Bank of India's (RBI) website.
Visit the home page of RBI at http://www.rbi.org.in.
In the home page as given in the below screen shot, just hover over your mouse point onto the circled place as shown below (no need to click on the 'Exchange Rate')
Past/Historical Foreign Exchange rates
By visiting the following link one can check and be able to download currency rates on various dates already
Upon specifying the range of date for the period for which exchange rates are required.
Foreign Exchange rate is also known as 'Reference Rate'.