Choose Edit->Signature->Insert->Your signature name
Infix places the image so that it’s white background remains transparent.
After initial placement, the signature image will need to be resized. Whilst holding down the SHIFT key, drag one of the resize handles to scale the image, retaining its original aspect ratio. If you do not hold SHIFT whilst scaling, you may stretch the signature out of shape.
The finished size of the signature image is recorded so that next time the signature is used, you should not need to resize it.
Signatures placed in this way are not annotations in the same way as sticky notes etc. They do not have associated pop-up note windows, do not appear in the comments panel and are always included during printing. They form part of the page unlike annotations which float in a layer above the page.