Create you own signature and add it to Acrobat Reader:
1) Sign a clean A4 paper and scan it as a picture.
2) Open the picture in e.g. Paint and cut out the signature. Save the signature as a jpg file.
3) Open the pdf document you want to sign in Acrobat Reader and click Fill & Sign
4) Click on Sign and Add Signature
5) Add your signature jpg file and click Apply
6) Now you can choose your signature and place it on the document.
Save your jpg signature file so that unauthorized persons cannot access it.