Bought a copy on VHS, released in 1983 under the title "The Witching", I believe this to be Necromancy (1972) but with some nudity and an alternative musical score added. A coven of occultists, headed by Orson Welles, are practicing Black Magic in order to bring back the dead and a young couple get caught up in the goings on
Central character is well played by Pamela Franklin as a young, paranoid women surrounded by Satanists, Rosemary's Baby being the first movie that springs to mind. Sadly Welles puts in a minimal, somewhat unconvincing performance. There is some good camera work and I liked the desert location, always popular in movies from this period featuring Devil worship. However the plot features holes and I found the ending disappointing and confusing. A second viewing may improve this.
Scream Queen Brinke Stevens can be seen as one of the naked witches.