  We use the radiative potential method to perform a detailed study of quantum
electrodynamics (QED) radiative corrections to electric dipole (E1) transition
amplitudes in heavy alkali-metal atoms Rb, Cs, Fr, and alkali-metal-like ions
Sr+, Ba+, and Ra+. The validity of the method is checked by comparing with the
results of rigorous QED in simple atomic potentials. We study the effects of
core relaxation, polarization of the core by the E1 field, and valence-core
correlations on QED, which are shown to be important in some cases. We identify
several transitions for which the QED contribution exceeds the deviation
between atomic theory and experiment.
