Is it possible to download a vf page by clicking custom button in salesforce?

Hi Deepak,

<apex:page id="MainPage"
           showHeader="false" 
           cache="true"
           contentType="application/x-pdf#Here-is-your-filename.pdf">

    <!-- Here comes another page with a content to be converted to PDF -->
    <apex:include pageName="PageThatGeneratesPdf"/>
</apex:page>

<apex:page showHeader="false"
           renderAs="PDF"
           cache="true">

<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />

<style type="text/css">
@page{
    size:A4 portrait;

    @bottom-right {
        content: "Page " counter(page) " - " counter(pages);
        font-family: 'Arial', 'Helvetica', sans-serif;
        font-size:10px;
    }
}
</stype>
</head>

Here is your main content ...

</apex:page>