Suppose that α ∈ (0, 2) and that X is an α-stable-like process on R d. Let µ be a signed measure on R d belonging to the class K d,α and A µ t be the continuous additive functional of X associated with µ. In this paper we show that the Feynman-Kac semigroup {T µ t : t ≥ 0} defined by T µ t f (x) = E x e −A µ t f (X t) has a density q µ and that there exist positive constants c 1 , c 2 , c 3 , c...