The phrase "adding that it contributes" is correct and usable in written English.
It can be used when you want to provide additional information or clarification about how something has a positive effect or adds value to a situation.
Example: "The researcher emphasized the importance of the new policy, adding that it contributes significantly to employee satisfaction."
Alternatives: "noting that it adds" or "mentioning that it enhances".
Later in the game's development, Shinichi Sakamoto came on board to compose its soundtrack; in an overview of the series by IGN, they said that the music "was a sigh of relief for those still haunted by the repetitive loops of the arcade original", adding that it contributed to the RPG style and that would establish the standard for all future Wonder Boy games in the series.
Grandjean said, "I would not call the dangers from mercury small," adding that it "very likely contributes to the development of heart disease".
(Adds that judge to hear case contributed to Hastert election campaigns, paragraphs 4-5).
On November 29th the Bank of England's Financial Policy Committee said that British banks may have underestimated how much capital they need to hold by as much as £35 billion ($56 billion), adding that this contributed to a lack of investor confidence in banks.
He added: "There's no doubt that it contributed to an atmosphere in which the only focus for weeks at a time, months at a time were Hillary's emails, the Clinton Foundation, political gossip surrounding the DNC".
It added that last quarter it contributed $789 million to its United States pension fund.
Wal-Mart credited strong sales in Britain, Canada and Mexico, adding that currency benefits contributed only a small part of the gain.
"They tend to have fewer resources," he said, adding that this divide contributed to a long-term problem of low minority representation in the ranks of the media industry.
On the flip side, an Information Ministry official told me the government was determined to support the media in combating corruption, adding that journalists had contributed to the resignation of a cabinet member after compiling adequate evidence about his misdeeds.
We intend to make the 21st century a world with no human rights violations against women," Abe said, adding that Japan is contributing $34 million over two years to efforts aimed at eliminating sexual violence against women during conflicts.
