ReportDocument report = new ReportDocument();
....
        report.Load(@"c:\....\report.rpt", OpenReportMethod.OpenReportByTempCopy);
....
        crystalReportViewer1.ReportSource = report;

        private void crystalReportViewer1_Navigate(object source, CrystalDecisions.Windows.Forms.NavigateEventArgs e)
        {
            if (e.NewPageNumber > 1)
                report.PrintOptions.PaperOrientation = PaperOrientation.Landscape;
            else
                report.PrintOptions.PaperOrientation = PaperOrientation.Portrait; 
          
        }