Note on the Evolution of the Gravitational Potential in Rastall Scalar Field Theories

We investigate the evolution of the gravitational potential in Rastall scalar field theories. In a single component model a consistent perturbation theory, formulated in the newtonian gauge, is possible only for $gamma = 1$, which is the General Relativity limit. On the other hand, the addition of another canonical fluid component allows also to consider the case $gamma eq 1$