A melhor maneira para gerar arquivos PDF pelo PHP é utilizando a biblioteca FPDF. Primeiramente entre em www.fpdf.org/ Depois para utilizar é bem simples você pode usar este código como exemplo:

<?php
// Get required files.
require 'fpdf/fpdf.php';

// Set some document variables
$author = "Me McMe";
$company_name = "APPLIED MATERIALS";
$name = "Liang Y. Chen, Ph.D.";
$title = "Corporate Vice President & General Manager";
$title_2 = "Alternative Energy Products Group";
$dept_div = "Energy & Environmental Solutions";
$phone = "T  408.563.6330";
$fax = "F  408.235.6989";
$email = "[email protected]";
$address2 = '3535 Garrett Drive, M/S 10071fdsfsdf';

// Create fpdf object
$pdf = new FPDF('L', 'mm', array(51,87)); //fpdf(orientation(L for Landscape), unit of measurement(mm for millimeters), 

// Add a new page to the document
$pdf->addPage('L', array(51,87));

$pdf->SetDisplayMode(real,'two');
$pdf->SetFont('Arial','B',5);
$pdf->SetTextColor(0,0,0);
$pdf->SetXY(0, 0);
$pdf->SetMargins(0,0,0);

$pdf->Cell(0,11, "$company_name", '1', 2, 'L', false);
$pdf->Cell(0,11, "$name", '1', 2, 'L', false);
$pdf->Cell(0,11, "$title", '1', 2, 'L', false);
$pdf->Cell(0,11, "$title_2", '1', 2, 'L', false);
$pdf->Cell(0,11, "$dept_div", '1', 2, 'L', false);
$pdf->Cell(0,11, "$phone", '1', 2, 'L', false);
$pdf->Cell(0,11, "$fax", '1', 2, 'L', false);
$pdf->Cell(0,11, "$email", '1', 2, 'L', false);
$pdf->Cell(0,11, "$address2", '1', 2, 'L', false);

$pdf->Image('amatlogo.gif', 0, 0, 23.28, 21.52, 'GIF');
$pdf->Output('simple.pdf','I');
?>