How to find Rf?

F4 fx =((B4-B3)/B4)*100 A B D E F G H 1 1 Return Adjusted Price WMT AAPL 2 Date MCD MCD WMT AAPL Rf 3 105.38 63.44 25.91 4 108.38 62.26 27.29 2.769 -1.895 5.063 5 109.14 60.55 28.60 0.693 4.557 11/1/2016 12/1/2016 1/1/2017 2/1/2017 3/1/2017 4/1/2017 5/1/2017 -2.830 5.907 6 113.66 64.35 32.28 3.980 11.417 7 116.26 65.39 34.00 2.232 1.595 5.055 -0.007 8 125.51 68.71 34.00 7.375 4.823 9 135.35 71.83 36.16 7.264 4.351 5.964