From a temperature study of coupling constants in cis and trans i-C$_3$F$_7$CH=CHF several coupling constants characteristic of the fixed rotamers have been calculated. The observed temperature dependence is consistent with there being only two rotamers of significant population for each isomer. The enthalpy difference between rotamers is -1700 and -900 cal/mole for the cis and trans isomers respectively. Long-range F-F coupling constants appear to be large where the interacting nuclei are in close proximity. Some of the coupling constants are found to be of opposite sign when the isomers change their conformations.