AppScript Code Version 1

function doGet() {
	var ss = SpreadsheetApp.openByUrl(
		 'https://docs.google.com/spreadsheets/d/1lPOwiYGBK0kSJXXU9kaQjG7WNHjnNuxy25WCUudE5sk/edit');
	SpreadsheetApp.setActiveSpreadsheet(ss);
	SpreadsheetApp.setActiveSheet(ss.getSheets()[0]);
	var title = ss.getSheets()[0].getRange("A1:A").getValues();
		var titles = [];
	var link = ss.getSheets()[0].getRange("B1:B").getValues();
		var links = [];
	var pubdate = ss.getSheets()[0].getRange("C1:C").getValues();
		var pubdates = [];
	var description = ss.getSheets()[0].getRange("D1:D").getValues();
		var descriptions = [];
	var author = ss.getSheets()[0].getRange("E1:E").getValues();
		var authors = [];
	for (i = 0; i < title.length; i++) {
		titles += "<item>" + "<title>" + title[i] + "</title>";
	}
	for (i = 0; i < link.length; i++) {
		links += "<link>" + link[i] + "</link>";
	}
	for (i = 0; i < pubdate.length; i++) {
		pubdates += "<pubdate>" + pubdate[i] + "</pubdate>";
	}
	for (i = 0; i < description.length; i++) {
		descriptions += "<description>" + description[i] + "</description>";
	}
	for (i = 0; i < author.length; i++) {
		authors += "<author>" + author[i] + "</author>" + "</item>";
	}

    return ContentService.createTextOutput(titles + links + descriptions + pubdates + authors)
	.setMimeType(ContentService.MimeType.RSS);
}