Create a list view button. Refer this link for how to create. https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_controller_sosc_custom_button.htm
You can select and pass the record id to page
you can generate a PDF now from the records selected . refer this link https://developer.salesforce.com/docs/atlas.en-us.pages.meta/pages/pages_quick_start_renderas_pdf.htm?search_text=pdf
You can do it in this way .