We worked out a figure of 709 for a doublehanded Stealth R. We converted from the SCHRS figure of 1.03 using a factor worked out by comparing the SCHRS and RYA PY handicaps for a Hurricane and for a Hobie 16 and averaging the answers. Or something like that. If you've got the bigger F16 sails it should be a bit lower - and if you're sailing singlehanded it should be lower again. Your club will be using the handicap as a "Trial Number" so they'll no doubt adjust the 711 downwards when you start to clean up!
George