Do you need to have your audience to sign an attendance list? You should keep control of this list to avoid that it becomes a distraction during your presentation. Most people can’t pay attention to what you are saying and sign an attendance list at the same time.
Having your audience sign the attendance list before your presentation is not always the best option as when people enter the room at different times some may miss signing the list as it is circulating around the room. Having it sign at the end of your presentation is also not the best as it is not a very powerful end of your presentation if you need to end with having to ask to sign an attendance list. This also could lead to people having to wait in line to sign the list.
If you know that people will arrive at different times, having an attendance list at the entrance of the room making sure everyone signs the list may be a good option. Also having the list sign during a break of your presentation may be a good solution. You can also think about a digital solution such as a QR code on screen or near the entrance that people need to scan with their mobile phone to sign for attending your presentation.
Make a good plan for having the members of your audience sign the attendance list. Keep control of the process to avoid it becomes a distraction for your presentation.