Should a rhetorical question end with a question mark?

Yes.

There are three choices: question mark, period (full stop), or exclamation mark, depending on the intonation required.

http://www.chicagomanualofstyle.org/qanda/data/faq/topics/Punctuation/faq0068.html

Punctuation is there to show how the sentence is to be read, denoting pauses, intonation, interpolations and so forth.
Many rhetorical questions need a rising intonation at the end, so a question mark is appropriate. Sometimes a falling intonation is sought with a period (full stop). Try saying the following out loud and notice how the intonation changes:
To be, or not to be ?
To be, or not to be !
To be, or not to be.
To be or, not to be ??

BTW when I started skool (and dinos roamed the earth) one of the beginner classes was named "2B", so we said:
2B, or not 2B?
Note the different pron!

There was at least one attempt to introduce a special typographical symbol for this case but it did not succeed. See https://en.wikipedia.org/wiki/Question_mark#Rhetorical_question_mark

In general, yes. But it is a little more complicated. If a question (also a rhetorical question) is an "indirect question", you can not use a question mark. Example: “The officer asked why I was speeding.” The sentence refers to a time that someone was asked a question. This sentence not a question, and a period is used.

Now look at this sentence: “We will leave at 7 p.m., won’t we?”
“We will leave at 7 p.m.” is a declarative sentence, that would end in a period. But, “won’t we?” makes it a question, and the use of a question is needed. This also applies to rhetorical questions.

Another example: “Will everyone please give their full attention to the speaker.” This sentence ends in a period, though technically this sentence is a question, but the speaker is actually saying “please give your attention to the speaker“. The request is formal, and the speaker is not looking to get a response. It's not like “Will you please be quiet?”, and the answer could be “Yes, we will.” It is a formal way of saying: Be quiet, the speaker is talking.” In formal requests (also rhetorical ones), we use a period at the end of a sentence rather than a question mark.

So, question marks are used at the end of sentence that are questions. More information can be found here: http://gedeasy.com/ged-rla-prep-question-marks/

Referring to rhetorical dialogue. If someone says “Be quiet, will you.” Does that require a question mark, because the person speaking doesn’t really want a reply?
Many thanks
Dave

It seems as though using a question mark and a period would denote that it should be voiced as a question but is intended to be understood as a statement.