Consider a simple script that after a while displays a button like this on your landing page:

When you click the button, the form for submitting a request will be displayed:

To install this script, move the callbacker folder to the main folder where your landing page is located.
Next, open the index file of your feed and connect the js and css files (insert it best before the closing head tag):
<link type=»text/css» rel=»stylesheet» href=»callbacker/css/css.css» />
<script type=»text/javascript» src=»callbacker/js/script.js»></script>
In case there is no jquery library on the landing, connect it by inserting the following text also before the closing head tag:
<script src=»https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js»></script>
If you want to increase the appearance time of the button or decrease it, then you need to open the file script.js and there will be a footnote describing where to change.
Well, after all these manipulations, in order to insert the block with the form and the button, you must copy the code from the attached file index.html wrapped in
<!- ->
<!- ->
and place it before the closing body tag.
P.S. Leyte in the plus and do not forget to configure the form itself to send leads (And send a donation, of course.)!