I participate in giving to such funds. First of all, you need Rabbinical endorsements, from a Rav who knows the family, etc.
Secondly, set up a “go fund me” page on one of the frum charity sites.
Next, spread the word.
How? Send to Yeshiva world News, Matzav, Vos Es Neis, and have someone you know, who has lots of “friends” to post on Facebook.
That is where I see such appeals. Including A rav from one of the leading yeshivas in J’lem, who needs/needed funds for his wifes’ medical treatment. (someone posted the appeal in/on Matzav & Facebook)
Much Hatzlacha