This RTF converts fine for me. See attached screencap. I've also attached the converted epub.
I'm also attaching the job details from my conversion. You could check it against your own conversion to see if you can tell where the differences in conversion settings might be.
Spoiler:
Convert book 1 of 1 (PGeBook)
Resolved conversion options
calibre version: 0.8.7
{'asciiize': False,
'author_sort': None,
'authors': None,
'base_font_size': 12.0,
'book_producer': None,
'change_justification': u'justify',
'chapter': u'//h:h1',
'chapter_mark': u'pagebreak',
'comments': None,
'cover': None,
'debug_pipeline': None,
'dehyphenate': True,
'delete_blank_paragraphs': True,
'disable_font_rescaling': False,
'dont_split_on_page_breaks': False,
'enable_heuristics': False,
'epub_flatten': False,
'extra_css': None,
'extract_to': None,
'fix_indents': True,
'flow_size': 260,
'font_size_mapping': u'9, 10, 11, 12, 14, 16, 20, 36',
'format_scene_breaks': True,
'html_unwrap_factor': 0.4,
'input_encoding': None,
'input_profile': <calibre.customize.profiles.InputProfile object at 0x0448C2F0>,
'insert_blank_line': False,
'insert_metadata': True,
'isbn': None,
'italicize_common_cases': True,
'keep_ligatures': False,
'language': None,
'level1_toc': None,
'level2_toc': None,
'level3_toc': None,
'line_height': 0.0,
'linearize_tables': False,
'margin_bottom': 5.0,
'margin_left': 5.0,
'margin_right': 5.0,
'margin_top': 15.0,
'markup_chapter_headings': True,
'max_toc_links': 0,
'minimum_line_height': 0.0,
'no_chapters_in_toc': False,
'no_default_epub_cover': False,
'no_inline_navbars': False,
'no_svg_cover': False,
'output_profile': <calibre.customize.profiles.SonyReaderOutput object at 0x0448C730>,
'page_breaks_before': u'/',
'prefer_metadata_cover': False,
'preserve_cover_aspect_ratio': False,
'pretty_print': True,
'pubdate': None,
'publisher': None,
'rating': None,
'read_metadata_from_opf': u'c:\\docume~1\\jackies\\locals~1\\temp\\calibre_0 .8.7_tmp_7xpmws\\calibre_0.8.7_lsdfyg.opf',
'remove_fake_margins': False,
'remove_first_image': False,
'remove_paragraph_spacing': False,
'remove_paragraph_spacing_indent_size': 1.5,
'renumber_headings': True,
'replace_scene_breaks': u'',
'series': None,
'series_index': None,
'smarten_punctuation': True,
'sr1_replace': None,
'sr1_search': None,
'sr2_replace': None,
'sr2_search': None,
'sr3_replace': None,
'sr3_search': None,
'tags': None,
'timestamp': None,
'title': None,
'title_sort': None,
'toc_filter': None,
'toc_threshold': 6,
'unwrap_lines': True,
'use_auto_toc': False,
'verbose': 2}
InputFormatPlugin: RTF Input running
on c:\docume~1\jackies\locals~1\temp\calibre_0.8.7_tm p_7xpmws\calibre_0.8.7_5vpryt.rtf
Converting RTF to XML...
Parsing XML...
Converting XML to HTML...
Parsing all content...
Parsing index.xhtml ...
Referenced file 'styles.css' not in manifest
Parsing styles.css ...
Generating default TOC from spine...
Merging user specified metadata...
Detecting structure...
Detected chapter: JANE EYREAN AUTOBIOGRAPHY
Detected chapter: PREFACE
Detected chapter: NOTE TO THE THIRD EDITION
Auto generated TOC with 3 entries.
Inserting metadata into book...
Flattening CSS and remapping font sizes...
Property: Unknown Property name. [34:2: -webkit-border-radius]
Source base font size is 10.00000pt
Cleaning up manifest...
Trimming unused files from manifest...
Parsing stylesheet.css ...
Property: Unknown Property name. [60:1: -webkit-border-radius]
Creating EPUB Output...
Splitting on page-break
Splitting on page-break
Splitting on page-break
Splitting on page-break
Looking for large trees in index.xhtml...
No large trees found
Split into 4 parts
Looking for large trees in jacket.xhtml...
No large trees found
Generating default cover
Removing anchor from TOC href: index_split_001.xhtml#calibre_toc_2
Removing anchor from TOC href: index_split_002.xhtml#calibre_toc_3
Removing anchor from TOC href: index_split_003.xhtml#calibre_toc_4
EPUB output written to c:\docume~1\jackies\locals~1\temp\calibre_0.8.7_tm p_7xpmws\calibre_0.8.7_7xtmmu.epub