We consider a thin-film limit for a three-dimensional phenomenological energy functional modeling the effects of a constant electric field on a bent-core liquid crystal in the ferroelectric smectic A-type phase. We show that similarly to what is seen in micromagnetics under a proper rescaling, the electric self-interaction terms give rise to boundary terms in the two-dimensional reduction. We also present numerical simulations based on the reduced model. This is a joint work with Carlos García-Cervera and Sookyung Joo.