From what I can find, William Rawle is attested, but I'm not seeing any evidence for his marriage to Elizabeth Kytson.
There is a pedigree in Rawle, Edwin John.. Records of the Rawle family. Taunton Somersetshire: Printed for private circulation by Barnicott and Pearce, 1898. which starts with this William, but gives no wife.
The Rawle family was at St. Juliot, Cornwall.
I doubt that Elizabeth Kytson has anything to do with this family.
She isn't the daughter of Sir Thomas, who did have a daughter named Elizabeth, but that Elizabeth married somebody else and died before he did, so couldn't have married a Rawle.
Here is the Thomas Kitson you were thinking of -- https://en.wikipedia.org/wiki/Thomas_Kitson -- interesting but not connected.