Haha! Interesting question because it actually depends on which country you are in!
The general answer is: Yes, the rank and file are expected to mention the donation arrangement in the door-to-door ministry.'
CLAM Workbook March 2016
March 21-27
Initial Call: wp16.2 16—Mention the donation arrangement. (2 min. or less)
https://www.jw.org/en/publications/jw-meeting-workbook/march-2016-mwb/meeting-schedule-mar21-27/
But, there are exceptions with how it is done
Letter: All Bodies of Elders 12 January 2016
Re: March Issue of the Life and Ministry—Meeting Workbook
From time to time, it may be necessary for us to write to each Congregation giving guidance on specific parts in the Life and Ministry Meeting Workbook. For example, during the week of March 21-27, under the section “Apply Yourself to the Field Ministry," the "Initial Call" assignment directs the student to mention the donation arrangement. As a reminder, in Britain and Ireland, we do not ordinarily raise the matter of donations unless the householder asks. Therefore, in this scenario the householder should enquire about the funding of our work and the student can then provide details regarding the donation arrangement.
I believe it is a legal red-tape thing in Britain - they can offer to 'sell' something for money at the door with no problem, but they can't simply ask for money at the door.
Please correct me - as I haven't got the time to research any web links - and feel free to give it to me with both barrels!
I've always understood that is why charity collectors in Britain often have a little sticker, pin or badge (or poppy) with them which they can offer to you - ie they can initiate the contact with you - and then they can ask if you'd like to contribute.
Also, as a side issue, I believe charity street-collectors are not meant to 'shake-the-tin' either.
Mind you, I don't believe the above is really enforced.