The most popular software for digitally signing PDFs is Adobe Acrobat Reader, but other options exist on PCs, Macs, the To apply an electronic signature click once in the box as instructed. Click StepSign up for a free trial at DocuSign, and then log in. Your first option is to type your name on the line and generate a font based signature. Adobe Document Cloud. Acrobat Sign. How to create an electronic signature. Sign PDFs online for free when you try the Adobe Acrobat PDF form filler. Here is