Include /bin when using serverless framework to upload to AWS

First question so hopefully I ask it right!

I am trying to include a binary file (pdftk) that a lambda function will call upon when invoked.

I am using serverless-webpack and cannot figure out how to include the /bin directory when deployig to AWS.

I'm new to this whole thing (programming, webpack, node..etc) but I've tried everything but am not sure if I need to update serverless.yml or webpack.config.js or both to require the /bin directly.

Any help much appreciated!

via Peter Schwarz