I have some of my articles that have been cited by other published authors but this has not been added to my citations on Google Scholar and ResearchGate.
You just have to wait until ResearchGate's and Google Scholar's automated algorithm will find more citations, but it may happen that they will never find all of them. There is no possibility to add citations "by hand". See also these discussions:
Dear Ekechi Stella Amadi As indicated by Wolfgang R. Dick the numerous questions here on RG discuss the various reasons why. See for example:
Article Case report of bullous pemphigoid in a 65 year old woman
has one citation here on RG:
Article Case report on localized bullous pemphigoid in two young females
while Google Scholar don’t recognize it because it is not listed in GS database.
In GS the paper has another citation:
Article Bullous Pemphigoid Masquerading as Erythrodermic Psoriasis
while it is not recognized by the search engine/algorithm of ResearchGate because the relevant (meta)data for this publication (especially the references including yours) are missing.
There is unfortunately not much you can do.
Best regards.
IF you still want to put some effort in this then you can try to upload the missing paper in GS in Academia.edu (the limited version can be used without any costs), this sometimes helps to get your paper listed/indexed in GS.
Furthermore you might try to contact the authors of the Bullous paper (this is a paper in a subscription journal https://wajmed.com/ojs3.3__wajm/index.php/wajmed/article/view/354 ) but perhaps they have a pdf file that they can upload here on RG (in the private mode) and then possibly the references will become included in the RG database.