Kepler-68d is a gas giant with the minimum mass about the same as Jupiter. It is at least a jovian-mass planet orbiting 1.4 astronomical units from its parent star, Kepler-68, well within habitable zone of the star.  It was detected by radial velocity.
After planets Kepler-68b and c were detected by observing planetary transits in front of its star, doppler spectroscopy measurements were used to make follow-up observations of the star. Kepler-68d was discovered using that method.