Porterfield registered 50 runs to help Ireland claim victory in Aberdeen
Ireland bowled Scotland out for 109 to win by 96 runs in the first one-day international in Aberdeen.
The tourists ended 205 for nine after losing the toss but restricted Scotland's batsmen to claim victory within 41 overs.
Fraser Watts, Navdeep Poonia and Ryan Watson were run out for three, four and 12 respectively as the Scots struggled.
Captain William Porterfield had earlier registered a half-century for Ireland, with Regan West taking four wickets.
Porterfield and Botha guided the visitors to 101 before the former was run out in the 24th over and Majid Haq bowled out Botha two overs later.
John Mooney (15) and Andrew White (32) fell to Ryan Watson, while Gordon Drummond took Trent Johnston (12) and Regan West (24).
West's ninth-wicket partnership of 36 with Alex Cusack took Ireland past the 200 mark before the home side were put into bat.
After Gavin Hamilton's 36 was ended by West, Watts was bowled out by Johnston before Poonia and Watson were run out.
Further wickets came for West as Neil McCallum (six), Gordon Goudie (12) and Ross Lyons (six) failed to make a dent in Ireland's lead.
The two second and final game of the series takes place on Sunday.