Your charger handles LiFe batts. As far as what charge rate, LiFe can be charged at 10-15C. 1C for this LiFe is 1.45amp. I think your charger is limited to 5amps so thats what to charge at - that would be about 3.5C.

If you had a more powerful charger, you could charge at higher rates, but charging at 5amps isn't going to be a prob either.