Please download the free Adobe PDF IFilter 6.0 from the Adobe Web site: http://www.adobe.com/support/downloads/detail.jsp?ftpID=2611
Run the installer and follow the instructions. After you finish the installation, rebuild the full-text search catalog that you created for Kentico CMS. Now you should be able to search PDF files.
Note 1: Adobe PDF IFilter is not a product of Kentico Software and we cannot guarantee its functionality.
Note 2: If you're using MS SQL Server 2005, you may need to run the following SQL commands so that the server can load PDF IFilter libraries:
sp_fulltext_service 'verify_signature', 0
GO
sp_fulltext_service 'load_os_resources',1
Page url: http://devnet.kentico.com/docs/devguide/index.html?searching_pdf_files.htm