If you're e-filing, you'll electronically sign your return, so no handwritten signature is required.
If you've printed your return to file by mail:
The new Form 1040 consists of 2 half-pages which TurboTax is printing as one page. You'll see the "Sign Here" spot near the middle of the page.
See screenshot.
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***