We've been through this recently in another thread. There's nothing you can do. It's because RG only identifies citations from people on its books. Google do a total search.
Google school counts self citation and other authors citation of your work, while researchgate does not count self citations as your citation. Also, researchgate has a list of journals it has indexed. Most of these journals are journals indexed in scopus, pubmed and Thomson Reuters now clavariate analytics. This implies that if the paper that cites your work is not indexed in scopus, pubmed and ThomsonReuters, it won't count it for you