  For distant stars, as observed by the NASA Kepler satellite, parallax
information is currently of fairly low quality and is not complete. This limits
the precision with which the absolute sizes of the stars and their potential
transiting planets can be determined by traditional methods. Asteroseismology
will be used to aid the radius determination of stars observed during NASA's
Kepler mission. We report on the recent asteroFLAG hare-and-hounds Exercise#2,
where a group of `hares' simulated data of F-K main-sequence stars that a group
of `hounds' sought to analyze, aimed at determining the stellar radii. Based on
the asteroseismic large frequency spacing, obtained from simulations of 4-year
time series data from the Kepler mission, we demonstrate that the stellar radii
can be correctly and precisely determined, when combined with traditional
stellar parameters from the Kepler Input Catalogue. The radii found by the
various methods used by each independent hound generally agree with the true
values of the artificial stars to within 3%, when the large frequency spacing
is used. This is 5--10 times better than the results where seismology is not
applied. These results give strong confidence that radius estimation can be
performed to better than 3% for solar-like stars using automatic pipeline
reduction. Even when the stellar distance and luminosity are unknown we can
obtain the same level of agreement.
