Acorn utilizes the OS X framework for printing.
File ▸ Page Set up
Adjust orientation (landscape, portrait), scale percentage, printer format, and paper size.
File ▸ Print
Adjust number of copies, two-sided, select a printer, and select presets.
For additional options when printing, open your image in the Preview Application. Additional scaling and layout options are available.
If a printer requires the image be saved as CMYK, go to File ▸ Export ▸ Export. Select JPEG, JPEG 2000, or TIFF as the file format. A checkbox option for CMYK will be present.
Prior to printing make sure your image dimensions and PPI are correct.