I believe the shortfall options arise when/if some holders don't take up the offer and their options then go into a pool to be purchased by others. To apply for these extra options just overpay the bpay amount. e.g. if you would like to apply for 200,000 shortfall options, pay an extra $200 (200,000 x $0.001). If you don't end up getting the shortfall options your extra money will be refunded. I'm not sure how they decide who gets the shortfall options.
IHL Price at posting:
10.3¢ Sentiment: Buy Disclosure: Held