>Hi,
>
>On the fly, I mean just distribute my rpt file to my customer and change my application system file so that my application will know of the new report file and allow my customer to view it like a add-on.
>
>I am think of implementing a flexible feature that allow me to update
>my application reporting feature by using distributing those rpt file only.
>
>If not, is there any other better suggestions.

IMO, the best way to do this is to have a report manager. It's a form that displays a list of reports from a DBF. The user then picks the report. To update, just send the new RPT file and the new ReportManger.DBF/CDX/FPT.

>
>BTW, I know that Crystal Report 8.5 allow user to modify their report on the fly, is it very flexible and easy for normal user to do it themselve ?

Not really. They need to know Crystal Reports. There is also additional licensing and royalties required to do this.