scoring question

[dt91307]

If a batter's at-bat is prolonged due to a fielder's error in foul territory (dropped routine fly ball in foul territory) then that batter subsequently hits a home run on the next pitch, how is it scored? Is the batter credited with a home run and the fielder who dropped the routine foul ball is charged with an error? How is it marked on the scorebook and input into iScore?

[OhioTex]

I do not have an official rule citation handy but here is how I would score this ...

The batter gets the home run
but it is unearned run

On the foul w error ...enter it in iScore like...

Foul> misc > assign error> tap player w error

[ETBill]

I do not have an official rule citation handy but here is how I would score this ...

The batter gets the home run
but it is unearned run

On the foul w error ...enter it in iScore like...

Foul> misc > assign error> tap player w error

Agree on the E+HR (unearned), provided it was actual misplay and not a tactical decision not to catch the ball (such as to prevent it from becoming a sac fly in bottom 9 of a tie game).
The rule is 2016 OBR 9.12(a) "The official scorer shall charge an error against any fielder: (1) whose misplay (fumble, muff, or wild throw) prolongs the time at bat of a batter..."