Report Ouput format at run-time

How the final user can select report output format at run-time.
For example:
The accounting manager select xls format for validations process.
The comercial manager need the same report but in pdf for send a email with the report.
Thanks in advance.

User ReportRunner.

ReportOutputDocument rep = reportRunner.byReportCode("FLAT_INFO")
    .addParam("entity", getEditedEntity())