Welcome to Apple Discussions,
A few things…
Is the 11x17 (tabloid) paper tray loaded in the printer?
Try going to Page Setup, select your printer, and then change the Paper size to Tabloid or 11x17
If you are trying to print the entire 11x17 on 8.5x11 paper… in the Acrobat print window, to the left of the Preview, click the Page scaling pop-down button and select Fit to printable area. (Notice that the preview will show the image of the page and the dimensions of your paper)
Hope this helps.