Yes, the concentration multiplier works with molecules.
If you want to learn more about the Document Grid you can look at the Custom Reports tutorial:
https://skyline.ms/wiki/home/software/Skyline/page.view?name=tutorial_custom_reports
The names of things like "Peptides" or "Molecules" change in the Document Grid when you switch the Skyline UI Mode ("View > User Interface") between "Peptides", "Small Molecules" or "Mixed", but the Concentration Multiplier column always has the same name.
In the Report Editor, you can search for columns using the binoculars button on the toolbar.
-- Nick