My broker withholds Canadian tax. I cannot tell you the effective rate but it shows up as a deduction on my brokerage transactions. Your dividend will be net of Canadian Tax. Then at the end of the year my broker prepares a 1099 with a foreign tax credit for all of those taxes I've paid. I'm my situation (which is probably typical), I'm able to take the entire credit on my 1040. So bottom line, there is no second round of taxation on PGH dividends by the U.S.
I'm not a tax expert and your circumstances may be different but I recall receiving 85% of the converted from Canadian to US dollar amount on divident payment day and then secured the 15% back on my return in the form of foreign tax credit. Not a bad deal if you ask me.