As part of a Kepler Guest Observer program to search for tertiary companions to close eclipsing binaries via eclipse timing, we are determining fundamental properties of the central binaries through radial velocity and light curve analysis. We have obtained moderate resolution blue spectra of 41 systems to produce double-lined radial velocity curves and spectroscopic orbital solutions. In addition, we reconstruct the spectra of the individual binary components and compare them to libraries of synthetic spectra to determine effective temperatures, surface gravities, and rotational velocities. Using these data and constraints we then model the Kepler light curves to determine the fundamental properties of each system. Here we present parameters for KIC 5738698, two F-type stars orbiting with a 4.8-day period.