Problem with Powerpoint VBA

Hi,
I have a Userform in vba powerpoint and the checkboxes in it, where I select the slides from presentation. I would like to have a possibility to select the particular slides and create a new pdf file. I already have a possibility do save the pdfs but I don’t know what kind of commands should I use to save the combination of particular slides. When I tried with a command “select” then I received the whole presentation, not the selected slides.

Could you help me what commands in the code should I use to achieve it?
Thank you in advance for your help