I would like to search for certain keywords in all articles which cite a given article. Is this possible? For example using google scholar somehow?
I am new here. Please forgive me if this question does not fit to the site.
Yes, Google Scholar has the functionality that you are looking for.
First, find the article that you want other papers to cite on Google Scholar, then click on the Cited by link.
Now, click on the Search within citing articles box, and either type your keywords into the search field (you may need to enclose your keywords in "quotes") or do an Advanced Scholar search and type your keywords in the appropriate field(s) there.