use AppleScript version "2.4" — Yosemite (10.10) or later
use framework "Foundation"
use framework "AppKit"
use scripting additions
use tvLib : script "tvLib"

set anImage to (current application’s NSImage’s imageNamed:(current application’s NSImageNameComputer))

set anAttachment to current application’s NSTextAttachment’s alloc()’s init()
anAttachment’s attachmentCell()’s setImage:anImage
anAttachment’s setBounds:(current application’s NSMakeRect(0, 0, 32, 32))

set img1Str to current application’s NSAttributedString’s attributedStringWithAttachment:anAttachment

set anAssrStr to makeRTFfromParameters("Piyomaru Software", 32, "Times") of me

img1Str’s appendAttributedString:anAssrStr

dispAttrStr("Main message", "Sub message", img1Str, 400, 80) of tvLib

on makeRTFfromParameters(aStr as string, aFontSize as real, aFontName as string)
　　set aVal1 to current application’s NSFont’s fontWithName:aFontName |size|:aFontSize
　　set aKey1 to (current application’s NSFontAttributeName)
　　
　　set aVal2 to current application’s NSColor’s blackColor()
　　set aKey2 to (current application’s NSForegroundColorAttributeName)
　　
　　set aVal3 to 0
　　set akey3 to (current application’s NSKernAttributeName)
　　
　　set keyList to {aKey1, aKey2, akey3}
　　set valList to {aVal1, aVal2, aVal3}
　　set attrsDictionary to current application’s NSMutableDictionary’s dictionaryWithObjects:valList forKeys:keyList
　　
　　set attrStr to current application’s NSMutableAttributedString’s alloc()’s initWithString:aStr attributes:attrsDictionary
　　return attrStr
end makeRTFfromParameters