Thanks guys, this is really helpful.
So then basically the name itself and the place name of origin do
need to agree in case? That was partly where I was confused, since I wasn't sure if the name needed to be in the nominative and the place needed to be in the genitive, since, for example it is 'Vettius Valens of
Antioch'. If all three can simply be put in the nominative case then that works for me though. It is just frustrating and somewhat surprising that there are no references for this anywhere.
The other issue is whether or not the article is necessary in front of the place name. This seems to vary from place to place from what I've seen, although I did find a couple of brief statements on page 290 of Smyth where he says that "Names of cities usually omit the article" and similarly with the names of nations when associated with persons. There still seems to be some confusion about the implementation of this in different sources though, such as on Wikipedia for example, where it varies from entry to entry. See their entry on Thrasyllus of Mendes
for example, where the article is used both before the name and before the city: "Thrasyllus of Mendes whose full name was Tiberius Claudius Thrasyllus ... (Greek: ὁ Τιβερίος Κλαύδιος Θράσιλλος or ὁ Θράσιλλος της Μένδης)." This entry is all in the nominative, but the question of whether or not the article must be used is even more acute.