Here's the method I use, very simple.

To add your sig to a photo. Write it by hand onto paper and scan into your computer. In photoshop make the sig black & white ensuring there are no mid tones and then copy & paste into your image, change your sigs shape by grabing the corners and reducing its size. Then you have to change the layer blending mode to Multiply to remove the white background, then flatten all layers.

__________________
Trevor

Camera: Pentax K10D
Lens: Pentax 18-55mm f3,5-5.6AL, Sigma 70-300mm f4-5.6 DG Macro,Keno 2x Converter,Extension Tubes.
Tripod: Velbon CX-440, Monopod.