Yes there is a way on the Mobile App to do this.
On the Mobile device while in front of the Customer, open the Quote, and tap on the "Approve" button at the top of the screen.
You will be asked to confirm this action, tap "Yes" to confirm.
Then tap the "Accept" button on the top of the screen.
You will once again be prompted to confirm this action. Tap "Yes" when prompted.
The next prompt will ask, "Do you want the customer to sign this quote?" Tap "Yes".
On the next screen, hand the device to the Customer to sign. If the person signing is different to the name that appears at the top of the screen, then alter this accordingly by tapping on it and entering the correct name.
The Customer can then sign using their finger on screen. When complete, tap the "Done" button top right of the screen.
This will save the signature and make it appear on the Quote when emailed or printed.