Open PDF File in Acrobat Reader rather than SAP Document Viewer.

Hello Experts,

Whenever we attach a pdf file using Services for objects-->Store Business documents, an attachment list list is created and the file is archived in the repository.

If we double click on it, the pdf is opened in SAP Document viewer and not in Acrobat Reader unlike word document....

Can anyone tell me what configuration changes should be made and where so as to open pdf file in Acrobat?