iPhone hand writing problem

If I choose the signer and the handwriting process for signature type, then the user can see the white window on his phone and apply his signature with his hand or with is electronic pencil (if available on his device). But the problem with an iphone is the default Safari browser overlap the "confirmation" button at the buttom of the iPhone screen so there is no apparent way to close the signature process and proceed to next steps... See attached screen capture.