terraform-provider-stackitprivatepreview/sample/sample.tfrc.example

provider_installation {
   dev_overrides {
      "registry.terraform.io/stackitcloud/stackitalpha" = "<CURRENT PROJECT PATH>/bin/"
   }

   # For all other providers, install them directly from their origin provider
   # registries as normal. If you omit this, Terraform will _only_ use
   # the dev_overrides block, and so no other providers will be available.
   direct {}
}