We analyse numerically manifestations of the radiative amplitude zero
(RAZ) effect in single leptoquark production associated with hard phot
on emission. We present some quantitative conclusions on the possibili
ty to distinguish leptoquark charges produced in ep collisions taking
account of three-body final state subprocesses and of proton structure
functions. Applying this method to HERA and possible LEP+LHC experime
nts we show that the RAZ analysis can serve as a tool to determine the
leptoquark electric charge up to large leptoquark masses.