There is no RDI table of DHA available, only the statement below as stated on the U.S. Food and Drug Administration page.
“In 2000, FDA announced a similar qualified health claim for dietary supplements containing EPA and DHA omega-3 fatty acids and the reduced risk of CHD. FDA recommends that consumers not exceed more than a total of 3 grams per day of EPA and DHA omega-3 fatty acids, with no more than 2 grams per day from a dietary supplement” (U.S. Food and Drug Administration, 2013).
U.S. Food and Drug Administration. (2013). FDA Announces Qualified Health Claims for Omega-3 Fatty Acids.