OK first thing is that against this raise PF, 77 is not the kind of hand you want to be playing.
The origional raise represents 1/6 of your opponents stack.. he either has a big hand or has committed himself to a bluff.
As is you have called it.
You have an open ended straight draw (8 outs) plus if you put your opponent on a over pair (AA KK QQ?) then you also have 2 outs for a set.
So lets say you have 9 outs which means that you need 2:1 odds
Calling is terrible.. you are beat and then paying to see only one card.. you will not be getting correct odds for that, and then will face a raise on the turn offering even worse odds.
My feeling is that the correct couse of action on the flop is to shove.
The pot is $3.22 and your stack is now $3.49 so its basically a pot sized shove.
If called the pot will be 8.50 and will have cost you about 3.50 .. so the odds are about 2.4:1
Which are correct odds to call.. so correct odds to shove with.
Plus you also generate a bit of fold equity.. occasionally he might fold with this hand so that further improves your odds of winning a little.
Shove the flop and hope for the best .. the odds are correct. TBH it would have been far more sensible to fold theis PF.. but as is...