Use SharePoint to record employee sign-off on documents

I am using SharePoint Online as a document management system. I have 25 users that are all employees under the same Office 365 subscription. I want an employee to read a document in the default SharePoint library, then somehow sign-off that they read the document. I can also start the process manually by starting a workflow that a specified employee must sign-off that they read a specified document.

The employee could approve something and SharePoint would record their approval, which document they approved, a time stamp, and their name. Ideally, I want to also have the option to sign-off myself that a certain employee read a document. I want to record data that somewhere and export it on-demand as a PDF or excel.

I’ve installed SharePoint Designer 2013 and SharePoint Online Management Shell. I’m a newbie in both.

I’m sure this is an easy solution that I cannot find. I researched and here are some possibilities already. I’m failing pretty hard at all of them right now.

• Use SharePoint Designer 2013 to create a custom approval Workflow.
  Workflow asks a user to select a document name from the default
  library. The Workflow then has the user approve it and records data
  like approval and time stamp on the Task List.
• Create a custom Form. Functions similar to above. Form saves data to
  a list.

Please help! I would greatly appreciate if you could point me at a relevant guide or someone who’s done this before. I’m sure it must exist out there.