David Ng said almost 4 years ago on Creating PDF files with WickedPDF :
Thanks for the prompt reply.  Two issues

1. image 
Same cod and same image, it works on the report, but image does not show on header.  The code is like this

  <table style="height: 50px; line-height: 3px;">
        <td style="width: 70px; padding-left: 00px;">
          <%=  wicked_pdf_image_tag image_url('HKT-logo.jpeg'), size: "125x125" %>
        <td style="width: 800px;">
        <h2 style="font-size: 30px;">SITES TESTING CO., LTD.</h2>

2. The variable
The same variable @sale is accessible in the report, but not accessible in footer.  
I tried HTML format, No Luck. The code

           header: { html: { template: 'users/header'....

Any ideas?