the codes listed here is part of the following article : https://www.mwordpress.net/blog-feed-and-freedom-of-choice-to-visitors/

create_feed_data.php

<?php
/*
 * Generate feedburner urls
*/
function create_feed_data($feed_list) {
	// create feed url for each category in given array
	foreach($feed_list as $feed_slug => $feed_name) {
		$feed_url = $feed_slug;
	}
	// create html input feed for each category in given array
	$feed_input = array();
	foreach($feed_list as $feed_slug => $feed_name) {
		$feed_input[] = "<input type=\"radio\" name=\"uri\" value=\"$feed_slug\">$feed_name\n";
	}
	// store data in array
	return array(
		'url' => $feed_url,
		'input' => $feed_input,
	);
}

default-form-feedburner.html

<form style="border:1px solid #ccc;padding:3px;text-align:center;" action="http://feedburner.google.com/fb/a/mailverify" method="post" target="popupwindow" onsubmit="window.open('http://feedburner.google.com/fb/a/mailverify?uri=wpportal-adsense', 'popupwindow', 'scrollbars=yes,width=550,height=520');return true">
	<p>Enter your email address:</p>
	<p><input type="text" style="width:140px" name="email"/></p>
	<input type="hidden" value="wpportal-adsense" name="uri"/>
	<input type="hidden" name="loc" value="en_US"/>
	<input type="submit" value="Subscribe" />
	<p>Delivered by <a href="http://feedburner.google.com" target="_blank">FeedBurner</a></p>
</form>

feed-url-list.php

<?php
$list = array(
	'wpportal' => 'الخلاصات كاملة',
	'wpportal-plugins' => 'تركيب الاضافات',
	'wpportal-adsense' => 'أدسنس',
	'wpportal-install-upgrad' => 'تركيب وترقية',
	'wpportal-lessons' => 'دروس',
	'wpportal-general' => 'عام',
	'wpportal-problem-and-solution' => 'مشاكل وحلول',
	'wpportal-tips' => 'نصائح',
	'wpportal-articles' => 'مقالات'
);
?>

final-form.php

<?php
$list = array(
	'wpportal' => 'الخلاصات كاملة',
	'wpportal-plugins' => 'تركيب الاضافات',
	'wpportal-adsense' => 'أدسنس',
	'wpportal-install-upgrad' => 'تركيب وترقية',
	'wpportal-lessons' => 'دروس',
	'wpportal-general' => 'عام',
	'wpportal-problem-and-solution' => 'مشاكل وحلول',
	'wpportal-tips' => 'نصائح',
	'wpportal-articles' => 'مقالات'
);
$feed = create_feed_data($list);
?>
<form action="http://feedburner.google.com/fb/a/mailverify" method="post" target="popupwindow"onsubmit="window.open('http://feedburner.google.com/fb/a/mailverify', 'popupwindow', 'scrollbars=yes,width=550,height=520');return true">
	<p>يمكنك الاشتراك في التصنيف الذي تحب :<br>
	<?php
		$data = $feed['input'];
		foreach($data as $inputs => $input) {
			echo $input;
		}
	?>
	</p>
	<p>أدخل بريدك الاإلكتروني : <input type="text"  name="email"/></p>
	<input type="hidden" name="loc" value="en_US"/>
	<input type="submit" value="اشترك الان" />
</form>