never used that app, you can however, if the app allows you, print that image to a virtual pdf printer, there is plenty of those in internet
the most common is pdfcreator
http
/www.pdfforge.org/pdfcreator
just be sure to install it but don't install the pdf architect or any adds or extras, you downloaded it just to have a virtual pdf printer that will create a pdf on your home documents or desktop, don't remember where it puts the resulting pdf