Write on PDF by Samsung Electronics, is a convenient PDF annotator for you. You can take notes by your own handwriting with a variety of Pen and tools.
Once installed and activated, it will list all PDF files in your device in one place. Then it allows you to annotate the file with your text and drawing content. You can save the pdf file thereafter and share the same. It also doubles up as a good pdf viewer.
This app is compatible with most Samsung Galaxy devices.
A very useful tool for annotation of pdf files on your phone.
Android : http://bit.ly/2vIr4cY