In plain English
FAR 52.223-4, Recovered Material Certification, is a solicitation provision prescribed at FAR 23.109(b)(1), most recently dated May 2008. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
This is a solicitation provision — it applies to offerors when submitting an offer, not to contract performance, so subcontract flowdown is generally not the operative question for it.
Where it's prescribed
As prescribed in 23.109(b)(1), insert the following provision:
Prescribing reference: FAR 23.109(b)(1).
The official text, verbatim
As prescribed in 23.109(b)(1), insert the following provision:
Recovered Material Certification (May 2008)
As required by the Resource Conservation and Recovery Act of 1976 (42 U.S.C. 6962(c)(3)(A)(i)), the offeror certifies, by signing this offer, that the percentage of recovered materials content for EPA-designated items to be delivered or used in the performance of the contract will be at least the amount required by the applicable contract specifications or other contractual requirements.
(End of provision)