For ACS Style you use superscript numbers within or after cited information
Example: Fluoridated water, as well as various fluoride products such as toothpaste, provide fluoride ions necessary for remineralization.²
The number you use will correspond to the citation you are referring to.
(Examples from the Williams College Library)
Prefer paper? Come to the library, where we have two copies of the ACS style guide on reserve behind the Help Desk.