Automator does the Job
I found that you can use Automator with the Action "New PDF from Images".
Open Automator, choose Service, Choose "image files" from the input dropdown menu from the Finder and add the Action "New PDF from Images". Save it as "Combine Images to PDF".
Now you can select images in the finder and rightclick > "Services" > "Combine Images to PDF"
Voila.
I have created a little Automator service, it takes all the images in a folder and combines them to a PDF titeled after the foldername. You can Download it here:
http://cl.ly/3A2R24060D0n3l1Z3U0m
To install, go to Finder, press SHIFT + CMD + G and enter
~/Library/Services and place the unpacked File there...