You can pass the id as part of the routeValues parameter of the RedirectToAction() method.
return RedirectToAction("Action", new { id = 99 });
This will cause a redirect to Site/Controller/Action/99.
Edit: 
For customizing url, you have to create custom route as:
routes.MapRoute(  "Project", // Route name
                   "{controller}/{Action}/{ProjectId}/{MachineName}/{CompanyId}", 
                   new { controller = "Project", 
                         action = "Directives", 
                         ProjectId= 0,
                         MachineName= "",
                         CompanyId = 0 
                       }  // Parameter defaults );
Use UrlParameter.Optional if you want any parameter optional.
Follow By Stephen Walthe article on ASP.NET MVC Routing
Refer this: RedirectToAction with parameter