Following is the step by step process describing the method I used to insert the signature into PDF. Hope someone else would also find it useful.
Step 1: import PDF into GIMP. Just drag and drop the PDF, the import dialog will appear. My default resolution was 100 pixels/inch. I increased it to 300 pixels/inch.
Step 2: Fill in the text using regular text tool from toolbox.
Step 3: Sign on a clear piece of white paper. Use your camera to take a picture of your signature. Open the picture in Gimp.
Step 4: In this step, we are going to remove the white background in your signature.
- Add Alpha channel to the background layer. This enables transparency.
- Use the "Select by color" tool (shortcut key - Shift+O). Ensure "Feathered edges" option is selected.
- Click on the background colour to select it. Ensure all background areas are selected. You can press down shift key and add to selection.
- Use Ctrl-X to remove the selected area. Press Ctrl-I to invert the selection. Now you should see only your signature selected.
- To enhance my signature, I used the airbrush tool to darken the signature. This is optional.
- Resize your image to required dimension. You could find out the required dimension by just selecting area where signature would go in and reading the dimension from status bar.
Step 6. You are all done. Just ensure all the layers are positioned as you want. Merge and save.