Go to the layout. Enter layout mode. Select the page size and orientation options you want for you PDF from Print or Page Setup.
Look for a dark verical line on the right hand side of your layout. This line represents the right hand edge of the printed or PDF page given current options you just selected. To not crop objects, you'll need to resize and reposition the objects on your layout to be to the left of this line or you'll need to modify your page size and/or orientation options.
Note that it is not uncommon in database systems to need layouts that are customized to the needs for printing or PDFing a given report with a separate layout for data entry.