SAN FRANCISCO — Tiger Woods appears set to make a rare putter switch on Thursday when the PGA Championship begins at TPC Harding Park. Woods has been practicing this week with a different version of the Scotty Cameron Newport II putter he has used for a majority of his career, one that allows him to change the weighting; it also is longer. Steve Stricker, who over the years has given Woods help with his putting, played a nine-hole practice round with Woods at Harding Park on Wednesday and liked what he saw. “I asked him about the putter switch,” said Stricker, the U.S. Ryder Cup captain who assisted Woods at the Presidents Cup last year. “It’s basically the same putter with a bit more flexibility. He’s able to change the weights around a little bit, but the length is the difference. “He’s got a little more length on there, and that’s just so he can practice a little bit more without back pain.