First, add American Chemical Society (ACS) citation style to your Zotero at this link:
Download the first option, "American Chemical Society."
Zotero is the best choice for Mac users. It also plays nicely with PC's.
At https://www.Zotero.org/download/, click to download BOTH Zotero AND the Zotero Connector. You need both tools, working together:
To export a citation from OneSearch, a library database, Google Scholar or another website to Zotero, make sure your Zotero desktop application is OPEN. Click on the title of the article (from your search results). Then click the button in the far right corner of your browser (circled here).
First, add American Chemical Society (ACS) citation style (see ACS style box to the left in this guide).
Within Word, to add a citation or Bibliography, click the Zotero button, and you can choose how to proceed:
When it gives you the option of Citation styles, choose "American Chemical Society":
If the method above does not work for in SciFinder for some reason, try this! Click the download arrow for the article in question:
Then, under "Download Reference Details," choose "Citation (.ris)."
It should go directly to the Zotero app, where you can choose where to file it.