Save RenderTexture as Texture

 void SaveRenderTexture(RenderTexture rd)
    {
        Texture2D screenShot = new Texture2D(rd.width, rd.height, TextureFormat.RGB24, false);
        RenderTexture.active = rd;
        screenShot.ReadPixels(new Rect(0, 0, rd.width, rd.height), 0, 0);
        RenderTexture.active = null;
        byte[] bytes;
        bytes = screenShot.EncodeToJPG();

        string nameOfTheImage = rd.name + ".jpg";
        // use   Path.Combine for platform independet / or \
        string pathToTheFile = Environment.GetFolderPath(Environment.SpecialFolder.Desktop) +
            "/" + UnityEngine.SceneManagement.SceneManager.GetActiveScene().name + "/" + "set01" + "/";
        if (!Directory.Exists(pathToTheFile))
        {
            Directory.CreateDirectory(pathToTheFile);
        }

        string fileName = pathToTheFile + nameOfTheImage;


        System.IO.File.WriteAllBytes(fileName, bytes);
    }