A new model for the shell structure of surfactants in droplet microemulsions is described in which the scattering length density distribution of the interface is treated as a Gaussian profile. The corresponding particle form factor and scattering intensity on an absolute scale are derived in analytical form for the case of both monodisperse and polydisperse droplets. It is compared with the more conventional model of concentric shells with sharp boundaries. We find that both models differ mainly in their high-q behavior. We use both models to describe experimental SANS spectra of droplet microemulsions in shell contrast. The new model proves to provide a more accurate description of the experimental data.