There is some discussion about the reason or source for reading the haftorah each week. According the Abudraham (Sefer Abudraham) the reason is because Antiochus (from the Chanukah story), (who not only brought pigs as sacrifices in the Bais Hamikdash but) forbade practicing Yiddishkeit and among the things he decreed was no learning/reading torah. As such, the Abudraham says the Jews of that time picked something from Navi that he wouldn’t recognize as being “the torah” and read something that related to the parsha of that week. Even after we were able to go back to reading the torah we continued to read the haftorah each week.
There is a discussion among the achronim about how we can read from something like chumash etc or sefer aftara (you should read from a safer torah like scroll that has just the haftaras [see gittin 60a]) that is not written on klaf with proper ink…the gemara says that a sefer aftara is permitted because it is impossible to demand that all written scriptures be written like a sefer torah (was too expensive etc.) the Taz says once the gemara allowed to use a sefer aftara since at that time was too expensive otherwise the kula nowadays still applies and can use a non-complete sefer. The Magen Avraham says that rule only ever applied to sefer torah and not for neviem (and the only discussion in the gemarah was about a kula/heter to not need write a full sefer tanach). There is a major halachick nafka mina that if we say like the Taz that it is based on a kula that we had no choice basically and now still suing it but either way is a kula, then the chasam sofer points out that when someone reads aloud in shul it is like he is reading baal pe and therefore he can’t be motzai others and they must read along themselves. However, acc to the Magen Avraham, he would be able to be motzai them.
According to Rabbi Hershel Schachter in speech or book, Lesser Known Laws of Torah Reading “In the event that the Haftarah is not being read from a parchment (Klaf), some authorities maintain that one can only fulfill his obligation by reading along with the Ba'al Maftir. According to these Poskim, if nine people have not recited the Haftarah along with the Ba'al Maftir, the Mitzvah of Keriat Hahaftarah has not been fulfilled.”
The Mishna Berura (284:11) brings the M”A that when the lainer is reading from a chumash etc should read together with him but not when reading from a klaf.
Hi Srul! Let me try to explain. The M"A held that there was only a need for a kula on navi in so far as being allowed to write over only parts of it, but that it never needed to be written on klaf and with proper ink etc, whereas for a torah you of course do need to write on klaf and with proper ink etc. The kiddush club ppl would be in bad shape according to either but acc to the taz they would need to read it along themselves, and shld do so quietly so not loud and disturbing bec the baal korei cant be motzai them according to the Magen Avraham they may not need to...
Now that i look back at that mishna berura he may be discussing a chumash vs a navi...I assumed that meant a klaf but I am not sure and need to understand that better...I definitely do see ppl reading along with the person reading haftorah so i need to find out...thanks for getting me to clarify this more.