Rantie, a £2.5million signing from Malmo in August, had only ever scored one previous goal, at Burnley in October, and his extravagant celebrations earned him a booking.
On Tuesday night's 2-1 victory he had only been on the pitch three minutes as a substitute for midfield player Andrew Surman and his first home goal came with a right-footed shot from Eunan O'Kane's pass which went in off a post.
Howe said: "It was a great moment for 'TK' and I am so pleased for him. I know he has struggled for goals since he came to us but I have had absolutely no doubts about his ability. I know what he can bring to the team.
"It was a question of him adapting to a new country, to the English game, to new team-mates and how we play. He is still doing that and we always knew it would take him time to settle and fulfil his great potential.
"Some of our supporters began to think we had made a mistake, but we have not. I just hope he scores many more like that because when he came on he was razor-sharp."
Howe felt Bournemouth should have won more convincingly, singling out Huddersfield goalkeeper Alex Smithies as the reason why it remained goalless until the 55th minute.
"One save he made from Elliott Ward was incredible," Howe added. "The rain made it very difficult but credit to my players for the way they carried on trying to play football in atrocious conditions."
Lewis Grabban put Bournemouth ahead with a penalty, sending the gallant Smithies the wrong way with his kick after Tom Smith had brought down Marc Pugh. Smith's punishment was worsened by a yellow card for the clumsy trip.
But Huddersfield, who badly missed the cutting edge provided by injured leading scorer James Vaughan, came back to level four minutes later.
New signing Nahki Wells created the opening and Calum Woods lashed home a fierce left-footed shot which gave home goalkeeper Lee Camp no chance.
After Rantie's goal Huddersfield had the chance to equalize again in stoppage time but Danny Ward failed to convert a chance set up for him by substitute Jon Stead.
Huddersfield boss Mark Robins admitted the lack of a genuine goal-scorer had contributed to another away failure.
"I am disappointed with the result," he said. "Our away from has not been good enough and we have to start picking up points on our travels.
"The rain made it difficult to play good football but overall I thought we had done enough to earn a draw, but not enough to have won.
"We played against a good footballing side who provide a lot of movement and are a different team to the one we beat 5-1 back in August.
"In the end we cannot get away from the fact that we were bare up top without Vaughan.
"We created a few chances but not many clear-cut ones and the only other disappointment was in the award of the penalty against us. I felt it was harsh and made worse by the booking for Tom Smith."