The Reserve Bank of India Friday fixed the Reference rate for the US currency at Rs 46.56 per dollar and the single European unit at Rs 63.85 per euro from Rs 46.09 per dollar and Rs 63.96 per euro respectively, of Thursday.In a note issued in Mumbai by the apex bank, the exchange rates of Great Britain's Pound and Japanese Yen against the Rupee have been quoted as Rs 73.2086 per pound and Rs 51.89 per 100 yen, respectively, based on the Reference rate for the US dollar and middle rates of the cross currency quotes at noon.The Reference rate is based on 12 noon rates of a few select banks in Mumbai and the SDR-Rupee rate will be based on this rate, the release added