Radix 2 square root

I am trying to understand the radix-2 square root shown in Chapter 6 of Digital Arithmetic(Miloš D.ErcegovacTomásLang). I am missing something in the computation of F[j]. I am attaching the formula used for F[j] and the example given in the textbook(for x = 0.10110111). Please help me in understanding how F[j] is computed.
F[j] formula
Square root example for x = 0.10110111