How to cite primary source first found in secondary source?

If I'm understanding correctly, you are saying you read a secondary source, which led you to a primary source; then you cited material from the primary source that wasn't discussed in the secondary source; and your question is whether you need to cite the secondary source because it led you to the primary?

If so, I do not think you need to cite the secondary source. It feels polite to do so, sort of like using "via" on Twitter. But in an academic paper I do not think it is required.

You cite the source you use, so if you use the primary souce then you reference that.

If you cite both then you reference both.

You don’t cite sources you don’t actually quote.