I have income from Hong Kong. Their tax basis is Apr1-Mar31. How can I claim foreign tax credit if I will file HK taxes AFTER I file Canadian? Also, do I prorate?

If it helps, Hong Kong usually charges a provisional tax for the following year. So for example, in 2017 they charged me provisional tax for 2018 (based on assumption of same income as 2017, which they will either refund if I made less or charge me more if I made more).