Check the Research check box, and use the Clinical Queries menu on the Advanced Search:
There is no easy way to specify quantitative studies in CINAHL.
Randomized Controlled Trials (check box or in the Publication Type menu) are often quantitative, or at least have a quantitative aspect.
With the Research check box, use the Publication Type menu:
Graph and Chart are available from the more limited Image Quick View check boxes (bottom of the Limits menu), as well. Results will be mostly 1-click full text, unlike the Publication Type menu options above.
These don't guarantee quantitative studies, but they help narrow things down.
You can combine these searches with other research-related options, such as the Age Groups, or Human/Animal studies options, or keywords related to types of studies, like 'phenomenology'.